S Further Click here to view this article's online features: • Download figures as PPT slides • Navigate linked references • Download citations • Explore related articles • Search keywords The China Shock: Learning from Labor-Market Adjustment to Large Changes in Trade 11 ■5 a, SC 1° s ° >3 o ^ ^■3 Annu. Rev. Econ. 2016. 8:205-40 First published online as a Review in Advance on August 8, 2016 The Annual Review of Economics is online at economics.annualreviews.org This article's doi: 10.1146/annurev-economics-080315-015041 Copyright © 2016 by Annual Reviews. All rights reserved JEL codes: E24, F14, F16, J23, J31, L60, 047, R12.R23 David H. Autor,1,2 David Dorn,3'4 and Gordon H. Hanson2'5 department of Economics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02142; email: dautor@mit.edu 2The National Bureau of Economic Research, Cambridge, Massachusetts 02138 3 Department of Economics, University of Zurich, CH-8001 Zurich, Switzerland; email: david.dorn@econ.uzh.ch 4Centre for Economic and Policy Research, London EC IV ODX, United Kingdom 5School of Global Policy and Strategy, University of California, San Diego, Lajolla, California 92093; email: gohanson@ucsd.edu Keywords globalization, labor-market adjustment, local labor markets, inequality Abstract China's emergence as a great economic power has induced an epochal shift in patterns of world trade. Simultaneously, it has challenged much of the received empirical wisdom about how labor markets adjust to trade shocks. Alongside the heralded consumer benefits of expanded trade are substantial adjustment costs and distributional consequences. These impacts are most visible in the local labor markets in which the industries exposed to foreign competition are concentrated. Adjustment in local labor markets is remarkably slow, with wages and labor-force participation rates remaining depressed and unemployment rates remaining elevated for at least a full decade after the China trade shock commences. Exposed workers experience greater job churning and reduced lifetime income. At the national level, employment has fallen in the US industries more exposed to import competition, as expected, but offsetting employment gains in other industries have yet to materialize. Better understanding when and where trade is costly, and how and why it may be beneficial, is a key item on the research agenda for trade and labor economists. 205 1. INTRODUCTION Mainstream economists have long argued that international trade improves welfare. Although trade may redistribute income, theory assures us that under standard conditions the gains to winners are more than sufficient to offset any losses incurred by those suffering adverse effects from foreign competition. Belief in the Pareto-improving nature of trade made economists frontline advocates for the broad-based liberalization of commerce that was embedded in the General Agreement on Trade and Tariffs (GATT) and other institutions built to manage the global economy after World War II (Bhagwati 1989). Paul Krugman states this view vividly in his 1997 Journal of Economic Literature article: "If economists ruled the world, there would be no need for a World Trade Organization (WTO). The economist's case for free trade is essentially a unilateral case: a country serves its own interests by pursuing free trade regardless of what other countries may do" (Krugman 1997, p. 113). Of course, introductory trade theory also teaches us that international trade is not generally Pareto improving. In their undergraduate textbook, Krugman & Obstfeld (2008, p. 64) write, "Owners of a country's abundant factors gain from trade, but owners of a country's scarce factors lose... [C]ompared with the rest of the world the United States is abundantly endowed with highly skilled labor and (...) low-skilled labor is correspondingly scarce. This means that international trade tends to make low-skilled workers in the United States worse off—not just temporarily, but on a sustained basis." For the first three or four decades of the Bretton Woods era, however, there was little occasion to scrutinize the benefits of trade. Most goods flows were North-North—between nations with relatively similar average incomes—which helped subdue distributional impacts. Views on how trade affects wages and employment turned less sanguine in the 1990s. As wage inequality rose, low-skill wages and employment fell, and manufacturing employment contracted in the United States, globalization was seen initially as a prime suspect. After vigorous inquiry, concern about the labor-market consequences of trade receded. Economists did not find trade to have had substantial adverse distributional effects in developed economies, either for low-skill workers specifically or for import-competing factors and sectors more generally.1 The broad sentiment that emerged in the literature was that labor-market developments were primarily attributable to technological changes that complemented high-skill workers and reduced labor demand in manufacturing. The impact of international trade on these outcomes seemed to be modest, at best. Several pieces of evidence favored these conclusions. First, the share of US employment in manufacturing had been in decline since the end of World War II, peaking at 39.0% of US nonfarm employment in January of 1944 and then falling decade after decade to a low of 8.6% in June 2015 (Figure 1). The disappearance of manufacturing jobs was nothing new. Second, the steep rise in wage inequality and fall in real wages of low-education workers in the United States and many other developed countries did not coincide closely with rising trade openness. As Feenstra (1998) and Learner (2000) note, the ratio of merchandise trade to GDP in the developed world rose steeply during the 1970s but stabilized thereafter, which greatly weakened the case for trade, having caused rising wage inequality and falling low-skill wages during the 1980s and early 1990s. Third, contrary to the predictions of textbook trade models, manufacturing industries in developed countries appeared to be substituting toward high-skill workers despite rising skill prices, suggesting that these industries were experiencing a skill-biased demand shift that emanated ^or formal surveys of the literature on trade and wages, see Feenstra & Hanson (2003) and Harrison et al. (2011). In developing economies, the labor-market impacts of globalization have been more diffuse (Goldberg & Pavcnik 2007). Autor • Dorn • Hanson 11 ■5 a, SC 1° s ° i3 o ^ „ 0.36 •S 0.12 J_I_I_I_I_I_I_I_I_I_I_I_I_I_I_l_ 1939 1944 1949 1954 1959 1964 1969 1974 1979 1984 1989 1994 1999 2004 2009 2014 Year Figure 1 Manufacturing share of US nonfarm employment (1939-2015). Source: FRED Economic Data (https:// research.stlouisfed.org/fred2/graph/?g = IGor). logically from the adoption of new technology (Berman et al. 1998). Although trade in the form of offshoring may produce such demand shifts, its modest scale in the 1980s and early 1990s meant that its estimated impacts were far smaller than those of investments in high-tech capital and equipment (Feenstra & Hanson 1999).2 Finally, simple factor-content calibration exercises— which rescaled traded-good imports into embodied labor imports—found that rising trade integration could account for only a small part of the fall in relative wages of low-skill workers in the United States (Borjas et al. 1997, Krugman 2000).3 When Richard Freeman asked in 1995 if US wages were "being set in Beijing," his answer was an emphatic no (Freeman 1995). The trade and wages debate reached something of a coda around the year 2000. The following is a reasonable summary of the contemporaneous consensus: 1. Trade had not in recent decades been a major contributor to declining manufacturing employment or rising wage inequality in developed countries; 2A further development, seen initially as damning for trade-based explanations of changes in labor-market outcomes, was the simultaneous rise in wage inequality in developed and developing economies (Berman et al. 1998). We now know that in the presence of offshoring (Feenstra & Hanson 1997, Grossman & Rossi-Hansberg 2008) or heterogeneous firms and skill-technology complementarity (Burstein & Vogel 2012, Sampson 2014), greater economic integration between countries may cause wage inequality to rise worldwide. 3 The usefulness of factor-content calculations for predicting labor-market outcomes was the subject of a spirited debate in the 1990s (Krugman 2000, Learner 2000). This debate has since been largely resolved by the discovery that a tight (although structurally model-specific) relationship between the factor content of trade and relative factor prices holds for a wide class of trade theories (Burstein & Vogel 2011). Tmvw.annualreviews.org • The China Shock 207 2. Workers employed in regions specializing in import-competing sectors could readily reallocate to other regions if displaced by trade; and 3. Due to the law of one price for skill, any labor-market impacts of trade would be felt by low-skill workers generally, not by trade-exposed workers specifically. A corollary of these observations is that trade should affect prevailing wage levels nationally but not employment rates locally or regionally. Moreover, given the presumed fluidity of US labor markets, even in the short- or medium run, the aggregate gains from trade in the United States should be positive.4 Just as the economics profession was reaching consensus on the consequences of trade for wages and employment, an epochal shift in patterns of world trade was gaining momentum. China, for centuries an economic laggard, was finally emerging as a great power and toppling established patterns of trade accordingly. The advance of China, as we argue below, has also toppled much of the received empirical wisdom about the impact of trade on labor markets. The consensus that trade could be strongly redistributive in theory but was relatively benign in practice has not stood up well to these new developments. Nor has the belief that trade adjustment is relatively friction-less, with impacts that diffuse over large skill categories rather than being concentrated among groups of workers in trade-competing industries or locations. In quantifying these impacts and adjustment frictions, recent evidence further suggests that the short- and medium-run adjustment costs demanded by large trade shocks are sizable entries in the accounting of gains from trade. China's rise has provided a rare opportunity for studying the impact of a large trade shock on labor markets in developed economies. An emerging literature on this topic offers a wealth of evidence and surprises that should catalyze and discipline research for many years to come. We believe that this evidence calls into question the consensus of the early 2000s and makes clear that, after the early Bretton Woods era aberration, the distributional consequences of trade are alive and well. Although these results do not at all suggest that international trade is in the aggregate harmful to nations—indeed, China's unprecedented rise from widespread poverty bears testimony to trade's transformative economic power—they make clear that trade not only has benefits but also significant costs. These include distributional costs, which theory has long recognized, and adjustment costs, which the literature has tended to downplay. Better understanding when and where trade is costly, and how and why it may be beneficial, is a key item on the research agenda for trade and labor economists. Developing effective tools for managing and mitigating the costs of trade adjustment should be high on the agenda for policymakers and applied economists. This review discusses findings from the rapidly growing literature on China's rise that have enriched our understanding of the impact of trade shocks on developed countries. We begin by discussing why China's long-awaited reemergence is helpful for studying the impacts of trade on labor-market outcomes. We then offer a simple theoretical framework that guides inquiry on measuring and interpreting these impacts. Next, we present evidence on how trade shocks originating in China have affected industries and plants, local labor markets housing those plants, and individual workers employed (or formerly employed) in those industries and local markets. We suggest how these results should cause us to rethink the short- and medium-run gains from trade. Finally, we argue that having failed to anticipate how significant the dislocations from trade might be, it is incumbent on the literature to more convincingly estimate the gains from trade, 4 Although these views may appear as a straw man, they are not. On point 1, see Baily & Bosworth (2014). On points 2 and 3, see Edwards & Lawrence (2013). And on the broader implications of these points, see President's Council of Economic Advisors (2015). Autor • Dorn • Hanson such that the case for free trade is not based on the sway of theory alone, but on a foundation of evidence that illuminates who gains, who loses, by how much, and under what conditions. 2. CHINA'S RISE On June 23, 1989, the Wall Street Journal marked the publication of its centennial edition by predicting what the global economy would look like 2 5 years hence. It selected the countries that it thought would be growth leaders and those it saw as future growth laggards. On the former list were Bangladesh, Thailand, and Zimbabwe. On the latter list was China, which, as the newspaper prognosticated, would fail to shake off "the stultifying bureaucracy of hard-line communism" (Anders 2014). The Wall Street Journal's predictions reveal just how uncertain China's future appeared in the late 1980s. After a decade of "reform and opening" under Deng Xiaoping, hardliners had reestablished control over economic policy. Their resurgence, fueled on the economic side by rising inflation and on the political side by the events at Tiananmen Square, caused reform to stall and cast doubt on China's market transition (Naughton 2007). Seen in this context, skepticism about China's future, although far off the mark from today's vantage point, would then have been entirely warranted. China's one-quarter century of dizzying export growth began once the reformist camp reaffirmed its authority over economic policy in the early 1990s. Deng, in one of the final political gambits of his career, launched his famous "southern tour" in 1992 to focus national attention on the successes of earlier policy experiments in a handful of locations on China's east coast (Vogel 2011). These efforts had included the creation of special economic zones (SEZs), which allowed foreign companies to set up factories that imported inputs and exported final outputs, relatively free from the interference of government minders (Yu & Tian 2012, Alder et al. 2013). As reformers retook the helm, China embraced global markets more fully, pushing the number of SEZs from 20 in 1991 to 150 in 2010. According to the World Bank, inflows of foreign direct investment, which had averaged only 0.7% of GDP during the 1980s, surged to 4.2% of GDP during the 1990s and 2000s. Production for foreign markets began a spectacular ascent, with China's share of world manufacturing exports growing from 2.3% in 1991 to 18.8% in 2013 (Figure 2; see also Storesletten & Zilibotti 2014 on the factors that have shaped China's development process). To provide context for China's reintegration into the world economy, we highlight key aspects of its recent performance that inform the analysis of attendant labor-market outcomes in developed countries. One is the idiosyncratic nature of China's transition from central planning to market orientation. The momentum of this transition—which has propelled China's trade—owes much more to dismal conditions in China at the time of Mao's death than to China's subsequent responses to contemporaneous shocks in high-income economies. Also important is the nature of China's postreform manufacturing surge. When and how China became "the global factory" are important for defining the scope and intensity of the China trade shock. Finally, there is the structure of global trade balances. China's penchant for running large current account surpluses has shaped the temporal distribution of trade gains and losses arising from its growth. 2.1. Making Use of Trade Shocks The interest of trade economists in China is driven both by its large quantitative importance as an exporter of manufactured goods and by the paucity of natural experiments in international trade. Among the most challenging issues for empirical analysis is that changes in trade policy in one country are often dictated by changes in the behavior of its trading partners. Consider the Tmvw.annualreviews.org • The China Shock -China's share of world manufacturing value added --China's share of world manufacturing exports *. 15 11 ■5 a, Figure 2 China's share of world manufacturing activity (1990-2012). Source: World Development Indicators (http://databank.worldbank.org/data/reports.aspxPsource = world-development-indicators). SC > n = ~Kn /Xi is the share of industry k in region z''s total sales on the US market, pn = Xn / -E* is the share of region i in total US purchases in industry k, and subscript c indexes China. For simplicity, we assume that Ajk = A/, — Qw{ and that trade costs remained unchanged.19 Equation 2 provides a reduced-form specification for estimating the impact of trade shocks emanating from China on regional economic activity in the United States or other countries. Most empirical analyses of the China trade shock base estimation on a specification similar to Equation 2 or its industry-level counterpart (see, e.g., Autor et al. 2013a,b and Pierce & Schott 2016). Of primary interest is the rightmost term of Equation 2, which captures the impact of growth in China's productive capacity on traded output by US region i. It can be rewritten as ^ 4>ikPckAck = ^2 4>ik XckAck (3) which is the weighted average exposure of region i to changes in US industry import penetration that is mandated by changes in China's production capabilities. During the 1990s and 2000s, advances in Chinese manufacturing were driven by the country's market transition, which gave its firms access to foreign capital, technology, and inputs; allowed capital to move from the public to the private sector; permitted rural-to-urban migration; and ended restrictions on direct exporting by private enterprises. The <$>n weights in Equation 3—the share of each industry in region z''s total sales on the US market—summarize differences in industry specialization patterns across US regions and thus capture variation in regional exposure to China's supply-driven export growth. 3.2. Identifying the Reduced-Form Impact of the China Trade Shock To estimate the impact of the trade shock in Equation 3 on regional labor-market outcomes, it is necessary to control for the confounding factors that also affect these outcomes. These confounds are summarized in the first four terms on the right of Equation 2. Anticipating the estimation approaches that we describe in Section 4, we discuss each of these components in turn. The first term on the right of Equation 2, Ylk't'ikEk, is regional exposure to US industry demand shocks. Because observed changes in import penetration from China will be affected by both the first and last terms in Equation 2, they will embody changes in both US product demand and China's supply conditions. Any reduced-form regression of changes in regional outcomes on regional trade exposure may thus be contaminated by US product demand shocks. Autor et al. (2013a,b) propose using Chinese import growth in other high-income markets as an instrument for the growth in US imports from China to isolate the foreign-supply-driven component of changes in US import penetration. Specifically, they instrument the observed change in US industry-level import penetration from China with a non-US exposure variable that is constructed using data on contemporaneous industry-level growth of Chinese exports to other high-income markets (Australia, Denmark, Finland, Germany, Japan, New Zealand, Spain, and Switzerland). Table 1 documents the operation of the Autor-Dorn-Hanson instrumental-variables strategy. The first column of the table shows that annual US imports from China increased by 304 billion dollars between 1991 and 2007, whereas imports from China grew by 235 billion dollars across the eight other high-income countries, offering comparable trade data for the full sample period. Both the United States and the other high-income countries experienced rising imports in almost all of 19The first assumption implies that the change in production capability for region i in industry k can be decomposed into the exogenous change in national productivity in industry & (Ak) and the change in wages in region i (wj), consistent with Eaton & Kortum (2002). We thus assume that the exogenous determinants of regional comparative advantage (e.g., the Eaton-Kortum productivity distribution location parameters) are unchanged. Autor • Dorn • Hanson Table 1 The number of Chinese imports in the United States and in eight other developed economies (1991-2007; in year 2007 billion US dollars), and their correlations with United States-China imports3 A Chinese imports Industries with import Correlation with (billion US$) growth US-China imports United States 303.8 385 1.00 Japan 108.1 368 0.86 Germany 64.3 371 0.91 Spain 23.2 377 0.68 Australia 21.5 378 0.96 Finland 5.7 356 0.58 Denmark 4.7 362 0.62 New Zealand 3.8 379 0.92 Switzerland 3.3 343 0.55 Average for eight non-US countries 234.7 383 0.92 aCorrelations of imports across 397 four-digit industries are weighted using 1991 industry employment from the NBER Manufacturing Productivity Database. the 397 harmonized four-digit manufacturing industries, and the pattern of import growth across industries is highly correlated between the United States and the other countries (correlation coefficient of 0.92). The remaining columns of the table show the same information separately for each of the eight other high-income countries. Remarkably, each of the comparison countries witnessed import growth in at least 343 of the 397 manufacturing industries, and industry patterns of imports are strongly correlated with the United States, with correlation coefficients ranging from 0.55 (Switzerland) to 0.96 (Australia). That China made comparable gains in penetration by detailed sectors across numerous countries in the same time interval suggests that China's falling prices, rising quality, and diminishing trade and tariff costs in these surging sectors are a root cause. A possible threat to this supply-based explanation for Chinese export patterns is that product demand shocks are correlated across high-income countries, in which case using cross-industry variation in China's penetration of other high-income markets as an instrument for US penetration could confound import growth with unobserved components of demand. Autor et al. (2013a,b) also utilize a gravity-based strategy that replaces the growth in US imports from China with the inferred change in China's comparative advantage and market access vis-a-vis the United States. This gravity approach differences out import demand in the purchasing country, thereby retaining supply and trade-cost-driven changes in China's export performance. The residuals from this regression approximate the percentage growth in imports from China due to changes in China's productivity and trade costs relative to the United States. Gravity and Fv7 estimates are similar, which suggests that correlated import demand shocks are not overly important for the estimation. In the second term on the right of Equation 2, f9u), is the endogenous change in wages in US region i resulting from external product-market shocks. Most empirical analyses exclude wages as an independent variable. Estimating Equation 2 without wages on the right-hand side captures the reduced-form impact of trade exposure on economic activity in region i that works either directly through changes in industry output or indirectly through feedback effects from changes in local wages (see Kovak2013 on the impact of trade shocks on wages in Brazil based on a specific factors model). Alternatively, estimating a version of Equation 2 that makes either the change in regional wages or the change in regional labor supply the dependent variable provides a test of the geographic mobility of labor in response to trade-induced labor demand shocks. Tmvw.annualreviews.org • The China Shock ll9 The third term on the right-hand side of Equation 2, Y2k fakA/,, captures exposure of region i to changes in national industry productivity. Another consequence of regions varying in their specialization patterns is that they will differ in their exposure to sector-biased technological progress. Are regions that are more subject to technology shocks also ones that tend to face greater import competition? It appears not. There is near-zero correlation between exposure to technological change and exposure to trade with China across US local labor markets (Autor et al. 2013b, 20 1 5).20 A related issue, to which we return in Section 4, is whether exposure to trade with low-wage countries induces firms to step up innovation, making technology endogenous to trade. Finally, the fourth term in Equation 2, Y2k 4>ik Yli'^c Pi'k-4'k, captures changes in production capabilities in other supplying countries. These changes may be in part a response to changes in supply conditions in China. If we exclude this term from the estimation, we model changes in supply capabilities in other countries implicitly as a reduced-form function of changes in industry productivity in China.21 The specification in Equation 2 does not comprise an input-output structure. The presence of intermediate inputs may affect the transmission of trade shocks within the United States. Consider the case of tire production. If rising imports of Chinese tires cause US tire producers to reduce their output, demand for US-made synthetic rubber and steel fiber, which are used as inputs in domestic tire production, may decline as well. The trade shock, which began in the US tire industry, would also affect domestic demand in the industries that supply inputs to US synthetic rubber and steel fiber producers, as the shock works its way up the production chain. A full accounting of the impact of trade shocks thus requires incorporating input-output linkages between domestic industries (Pierce & Schott 2016, Acemoglu et al. 2016). A related possibility is that US synthetic rubber and steel fiber producers may benefit from access to lower-cost inputs from China. Recent literature allows for both channels of transmission, from US final goods producers to their domestic input suppliers and from Chinese input suppliers to US input buyers. To summarize this discussion, identifying the impact of trade with China on US local labor-market outcomes requires a valid instrumental variable—or, more broadly, a source of plausibly exogenous variation—for regional exposure to import competition, controls for regional exposure to technological change, and recognition that the estimated reduced-form impact may be attenuated by labor migration between regions. An alternative approach to identification is to utilize changes in imports that result from changes in trade policy. Topalova (2010), Kovak (2013), and McLaren & Hakobyan (2016) estimate the change in local incomes or employment due to greater import competition that arises from tariff reductions mandated by trade reforms in India, Brazil, and North America, respectively. Tariff reductions are a less obvious source of the increase in imports from China by developed economies. By the early 1990s, most developed nations, including the United States, already provided China with MFN access to their markets, implying an average import tariff of less than 4%. Trade barriers in these countries did decline in the late 1990s and 20 Autor et al. (2013b, 2015) measure regional technology exposure using an occupational composition index that captures the opportunities for substitution of computers for workplace tasks. This index is highly correlated with measures of computer adoption (Autor & Dorn 2013), but it is necessarily incomplete and would not be expected to capture industry-specific innovations that deviate from the overall pace of machine-labor substitution. 21 China's manufacturing growth is closely related to the expansion of global production networks in East Asia (Hsieh & Woo 2005). As China has grown, so too has its demand for imported inputs, which it assembles into final outputs for shipment abroad. During the 2000s, approximately half of China's manufacturing exports were produced by export processing plants, which are dedicated solely to assembly of imported components (Yu & Tian 2012). Over time, China has begun to produce an ever greater fraction of the inputs that it uses in export production, as it diversifies away from pure processing trade (Brandt & Morrow 2014). Koopman et al. (2012) estimate that the share of domestic value added in China's total exports—the fraction of China's exports composed of value added in China—rose from 50% in 1997 to 62% in 2007. Autor • Dorn • Hanson early 2000s, as a result of the Uruguay Round of the GATT, but the average decline was less than two percentage points, except in apparel and textiles (Bloom et al. 2016). Hence, changes in applied tariffs would seem to predict no more than modest growth in China's shipments to the United States. We discuss below how the observed reduction in US MFN tariffs may not capture the full impact of changes in US trade barriers on imports from China (Pierce & Schott 2016). 4. LABOR-MARKET ADJUSTMENT TO TRADE If we suppose that the growth in US manufacturing imports from China was triggered by a combination of productivity growth and improving foreign market access for Chinese firms, the shock that originated across the Pacific would first manifest itself in the United States in terms of more intense competition in product markets. Next, the shock would be transmitted to the regions in which competing manufacturing industries are concentrated, to the US sectors that supply these industries with inputs, and to the workers employed in manufacturing and its supplier industries. In this section, we empirically trace out the impacts of the China trade shock by examining consequences at each of these levels. 4.1. Industry Adjustment to Import Competition The initial point of transmission of supply shocks in China to factor markets in the United States is the product market. Improvements in China's productive capabilities and reductions in its trade costs will change the intensity of competition for US goods, leading to a contraction in US industries subject to greater import exposure. Bernard et al. (2006) use data on US manufacturing plants for 1977 to 1997 to examine the consequences of increased exposure to import competition from low-wage countries, which they measure as the share of these economies in US imports, and which is largely attributable to China.22 They find that over five-year intervals, industries facing greater increases in exposure to trade are subject to higher rates of plant exit.23 Among the plants that survive, those in more trade-exposed sectors have larger reductions in employment and a higher likelihood of changing their primary four-digit manufacturing category. Acemoglu et al. (2016) provide a complementary analysis to Bernard et al.'s (2006) that moves the focus to the industry level and extends the data forward in time to cover the period 1991 to 2011.24 Consistent with the logic of Equation 2, they estimate the following model for the impact of shifts in trade exposure on manufacturing employment: A LJr =aT+Pi AIPjT + yXj0 + eJT. (4) Here, ALjT is 100 times the annual log change in employment in industry j over subperiod r, AIPjr is 100 times the annual change in import penetration from China in US manufacturing 22This measure does not correspond to the theoretical concept of import penetration in Equation 3. However, because most of the temporal variation in the Bernard et al. measure is in the numerator—due to China's massive export growth—the share of US imports from low-wage countries and the change in US import penetration due to low-wage countries are highly correlated. 23 Similar effects are observed for other countries: Growing Chinese import competition increases plant exit and reduces firm growth in Mexico (Iacovone et al. 2013, Utar & Torres-Ruiz 2013) and reduces employment growth in Belgian firms (Mion & Zhu 2013), Danish firms (Utar 2014), and in a panel of firms from 12 European countries (Bloom et al. 2016). 24In related work, Pierce & Schott (2016) compare sectors that varied in their vulnerability to China's joining the WTO. Prior to the 2001 accession, Congress decided annually whether to rescind MFN status on China and impose much higher non-MFN tariffs. Relative to pre-2001 trends, employment declines after 2001 were greater in US manufacturing industries that had larger initial gaps between MFN and non-MFN tariffs. Tmvw.annualreviews.org • The China Shock Table 2 Industry-level changes in Chinese import exposure and US manufacturing employment3 1991-2011 1991-1999 1999-2011 1999-2007 2007-2011 Mean (SD) Median Mean (SD) Mean (SD) Mean (SD) Mean (SD) 100 x Annual A in US exposure to 0.50 0.14 0.27 0.66 0.84 0.30 Chinese imports (0.94) (0.75) (1.33) (1.61) (1.68) 100 x Annual log A in employment -2.71 -2.05 -4.32 -0.30 -3.62 -5.73 (manufacturing industries) (3.07) (3.85) (3.49) (4.15) (5.02) statistics are based on 392 four-digit manufacturing industries. The change in US exposure to Chinese imports is computed by dividing 100 times the annualized increase in the value of US imports over the indicated period by 1991 US market volume in that industry. Employment changes are computed in the County Business Patterns. All observations are weighted by 1991 industry employment. Table adapted from table 1 in Acemoglu et al. (2016). industry/ oversubperiod r, f$i is the estimated effect of exposure to import competition on industry employment, Xjo is a set of industry-specific start of period controls (suppressed initially), aT is a period-specific constant, and ejr is an error term.25 Table 2, reproduced from Acemoglu et al.'s results, shows that the employment-weighted mean industry saw Chinese import exposure rise by 0.5 percentage points per year between 1991 and 2011, with more rapid penetration in the period of 1999 through 2007—during China's WTO accession—than from 1991 through 1999.26 Growth from 2007 to 2011 indicates a marked slowdown in import expansion following the onset of the global financial crisis, which halted trade growth worldwide (Levchenko et al. 2010). Table 2 also shows that the decline in US manufacturing employment accelerated over time: The average industry contracted by 0.3 log points per year between 1991 and 1999, by 3.6 log points per year between 1999 and 2007, and by 5.7 log points per year in the Great Recession period of 2007 to 2011.27 Table 3, also based on Acemoglu et al. (2016), presents estimates of Equation 4 in stacked first differences for the two time periods 1991-1999 and 1999-2011. For these results, the change in import penetration and a dummy for each time period are the only regressors. In column 1, which estimates the model without instrumentation, the import penetration variable is negative and highly significant, consistent with the hypothesis that rising import exposure lowers domestic industry employment. Nevertheless, this ordinary-least-squares point estimate could be biased because growth in import penetration is driven partly by domestic shocks. Column 2 instruments the observed changes in industry import penetration with contemporaneous changes in other-country China imports, as described above. The estimate in column 2 implies that a one-percentage-point rise in industry import penetration reduces domestic industry employment by 1.3 log points (/-ratio of 3.2). Column 3, which stacks the periods 1991-1999 and 1999-2007, shows that the coefficient of import penetration is similar if we restrict attention to the years preceding the Great Recession. Although it is clear empirically that employment in import-competing US industries has shrunk in the face of China's rapid growth, the challenge for research is how to measure the distributional 25Import penetration is defined here as AIPjz — AMj T /(Yj^i + Mj^i — £7,9i), where Yj is domestic output, Mj is imports, Ej is exports, and AM^ is the change in US imports from China. 26Table 2 slightly aggregates the 397 manufacturing industries of Figure 4 to 392 industries to improve compatibility with other industry-level data such as the Bureau of Economic Analysis (BEA) input-output tables. 27Ebenstein et al. (2014) describe how employment conditions change in the industries and occupations that are more exposed to US multinational companies moving production offshore. In mild contrast to the above results, they find that trade exposure affects employment not through workers' industry of employment but through their occupation of employment. Autor • Dorn • Hanson Table 3 Effect of import exposure on log employment change in US manufacturing industries (in OLS and 2SLS estimates)3 Stacked first differences 1991-2011 1991-2007 Without With Stacked periods 1991-1999 and instrumentation instrumentation 1999-2007 100 x Annual A in US exposure to -0.81***b -1.30 -1.24 Chinese imports (0.16) (0.41) (0.37) 1 {1991-1999} -0.08 0.05 0.04 (0.36) (0.36) (0.36) 1 {1999-2011} -3.79*** -3.46"* (0.33) (0.33) 1 {1999-2007} -2.58*** (0.38) Estimation method OLS 2SLS 2SLS Abbreviations: OLS, ordinary least squares; 2SLS, two-stage least squares. W — 784 (392 four-digit manufacturing industries over two periods (1991-1999 and 1999-2011 or 1999-2007). Employment changes are computed in the County Business Patterns and are expressed as 100 x annual log changes. Observations are weighted by 1991 employment. Standard errors in parentheses are clustered on 135 three-digit industries. Table adapted from table 3 in Acemoglu et al. (2016). h*p < 0.10, "p < 0.05, '"p < 0.01. consequences and the net economic costs and benefits of these labor-market impacts. The answers revolve around mechanisms that are not self-evident from the basic facts above; specifically, 1. Given the spatial concentration of manufacturing, do industry shocks translate into localized employment shocks—and if so, are they offset or amplified by local labor-market mechanisms? 2. To what extent are trade-induced industry employment contractions offset by employment gains elsewhere in the US economy, potentially outside of trade-impacted regions? 3. Do trade adjustments occur on the employment margin, the wage margin, or both? If on the employment margin, what are the costs to individual workers and to the public at large? 4. Are the costs of trade adjustment borne disproportionately by workers employed at trade-impacted firms and residing in trade-impacted local labor markets? Or do these shocks diffuse nationally, thus moderating their concentrated effects? We consider these questions below, highlighting both what is known and what remains unanswered. 4.2. Regional Employment Impacts To assess the distributional consequences of rising trade with China, we turn next to adjustments in local labor markets. Local exposure arises from the tendency of industries to cluster in specific regions of a country (Ellison et al. 2010). In the United States, manufacturing employment is particularly concentrated in parts of the Midwest and Southeast. Even within these manufacturing regions, there is wide variation in the industry composition of local firms. Industry composition may be affected by trade shocks, however. In measuring regional trade exposure, we follow the literature in utilizing data on regional industry specialization patterns in the preshock period, thus preempting any endogenous adjustment of industry location to contemporaneous trade shocks. Tmvw.annualreviews.org • The China Shock Autor et al. (2013a,b) examine the impact of Chinese competition on US commuting zones (CZs), drawing on data from the US Census, the American Community Survey, and the County Business Patterns for the years 1990 to 2007. CZs are clusters of counties that have the commuting structure of a local labor market (Tolbert & Sizer 1996, Autor & Dorn 2013). Figure 6 shows the spatial distribution of exposure to increases in Chinese import competition from 1991 to 2007 across CZs. In the map of unconditional import exposure in panel a, some broad regions have greater vulnerability to imports simply because they are more specialized in manufacturing overall. For instance, Alabama and Tennessee, both strongly manufacturing oriented, have a preponderance of trade-exposed CZs. Variation of trade intensity within regions becomes larger in Figure 6b, which plots import exposure conditional on the share of manufacturing in CZ employment as of 1990, thus measuring import competition for the local set of manufacturing industries. When looking within manufacturing, Tennessee, owing largely to its concentration of furniture producers, is far more exposed to trade with China than is Alabama, which has agglomerations of relatively insulated heavy industry. This variation of import exposure within local manufacturing sectors is the basis for much of the econometric analysis we discuss. Over the period 1990 to 2007—considered either as a single long difference or as stacked changes for 1990 to 2000 and 2000 to 2007—CZs that were more exposed to increased import competition from China experienced substantially larger reductions in manufacturing employment. Columns 1 to 4 of Table 4, based on Autor et al. (2013a,b), show that the decline in manufacturing jobs was largely accommodated by an increasing share of a CZ's working-age population that was unemployed or out of the labor force. Specifically, a $1,000 increase in a CZ's per-worker import exposure reduces the fraction of the working age population employed in manufacturing and nonmanufacturing, respectively, by —0.60 and —0.18 percentage points (the latter of which is not significant), and raises the fraction of unemployed and out of the labor force by 0.22 and 0.55 percentage points.28 Autor et al. (2013a,b) further document that this finding holds for workers at all education levels. For workers with less than a college education, increased trade exposure also predicts significant reductions in CZ employment in nonmanufacturing industries, suggesting the presence of negative local demand spillovers. Column 5 of Table 4 further shows that import competition has modest effects on the size of the working-age population in CZs. Tracing individual workers over time, Autor et al. (2014) confirm that there is little geographic migration in response to the trade shock.29 Thus, the industry-level impacts of Chinese import competition seen in Table 3 are equally visible within local labor markets. Contrary to the canonical understanding of US labor markets as fluid and flexible, trade-induced manufacturing declines in CZs are not, over the course of a decade, largely offset by sectoral reallocation or labor mobility. Instead, overall CZ employment-to-population rates fall at least one-for-one with the decline in manufacturing employment, and generally by slightly more. These results run counter to a precept of general equilibrium trade theory that the local employment effect of sectoral demand shocks should be short-lived, as the forces of wage and price arbitrage and labor mobility dissipate these shocks nationally. 28The import per worker measure is a variant of Equation 3 that uses data on local employment by industry to proxy for the sales and expenditure variables 4>ik and Ek- It can be interpreted as assigning national imports by industry to CZs based on CZs' shares in national industry employment, and normalizing the imports assigned to a CZ by total CZ employment. A $1,000 increase in annual imports per worker during a decade corresponds approximately to the difference in the trade exposure between CZs at the 75th versus 25th percentile of import exposure during 1990-2007. 29Population responses to local trade shocks are also limited in other countries. Analyses from Germany (Dauth et al. 2014) and Spain (Donoso et al. 2014) both find weak and statistically insignificant population adjustments in local labor markets that are exposed to import competition from low-wage counties. Autor • Dorn • Hanson □ Third quartile O G ^ o H Highest quartile (most exposed) § t| Geographic exposure to trade shocks at the CZ (commuting zone) level, (a) Quartiles of unconditional < §L Errata < An online log of corrections to Annual Review of Economics articles may be found at http://www.annualreviews.org/errata/economics Contents