Mass Migration and Technological Change∗ David Andersson† Mounir Karadja‡ Erik Prawitz§ First version: May 18, 2016 This version: February 18, 2020 Abstract This paper studies the effect of emigration on technological change in sending lo- cations after one of the largest migration events in human history, the mass migration from Europe to the United States in the 19th century. To establish causality, we adopt an instrumental variable strategy that combines local growing-season frost shocks with proximity to emigration ports. We document two sets of results. First, using novel data on technological patents, we find that emigration led to an increase in innovative activ- ity in sending municipalities. Moreover, the increase in innovation is coupled with an increased adoption of new technologies in both the agricultural and industrial sectors. Second, in terms of local economic development, we find that emigration led to higher unskilled wages in agriculture, a shift towards employment in the nascent industrial sector, a larger presence of incorporated firms, as well as higher tax revenues. JEL Codes: O15, O31, O33. ∗This paper was previously circulated as Mass Migration, Cheap Labor, and Innovation. We thank Torsten Persson, David Str¨omberg, Jakob Svensson, Philippe Aghion, Konrad Burchardi, Davide Cantoni, Jon de Quidt, Nathan Lane, Andreas Madestam, Peter Nilsson, Nathan Nunn, Maria Petrova and Per Pettersson- Lidbom, as well as numerous seminar and conference participants for helpful comments. We acknowledge funding from the Jan Wallander and Tom Hedelius Foundation and the Marianne and Marcus Wallenberg Foundation. †Department of Business Studies, Uppsala University and Department of Management and Engineering, Link¨opingUniversity. E-mail: [email protected] ‡Department of Economics, Uppsala University. E-mail: [email protected]. §Research Institute of Industrial Economics. E-mail: [email protected] 1 1 Introduction Emigration is often depicted as a major problem for developing countries. While they may lose human capital and reduce their available labor force, the economic effects of migration on origin regions left behind are theoretically ambiguous and surprisingly understudied.1 In theory, emigration may affect their economic development, and not least technological progress, for several reasons. It may be negatively affected if high-skilled emigration lowers the level of human capital (see, eg., Kwok & Leland, 1982) or positively affected if returns to schooling increase (Beine, Docquier & Rapoport, 2008) or migrants return home with ac- cumulated human capital (Borjas & Bratsberg, 1996; Mayr & Peri, 2008; Dustmann, Fadlon & Weiss, 2011). Emigration may also affect the incentives for technological change through increased labor costs due to labor scarcity (Elsner, 2013) or to stronger bargaining strength of workers (Karadja & Prawitz, 2019). On the one hand, labor scarcity and increased labor costs could discourage the creation of new technologies by reducing firm profits, the workforce that may use the inventions as well as the number of potential inventors (see, eg., Ricardo, 1951; Romer, 1990; Jones, 1995). On the other hand, a long-standing hypothesis posits that high wages may induce innovation and the adoption of new labor-saving technologies (Hicks, 1932; Habakkuk, 1962; Acemoglu, 2010; Alesina et al., 2018). In the long-run, such changes may in turn engender structural transformation and economic development (see, eg., Allen, 2009; Bustos, Caprettini & Ponticelli, 2016; Bustos, Garber & Ponticelli, 2017). This paper investigates the long-term effects of emigration on technological change in sending communities. To our knowledge, this is the first paper to study how emigration affects both the adoption and the innovation of new technologies. Our analysis takes a historical perspective and examines one of the largest migration episodes in history: the Age of Mass Migration. Between 1850 and World War I, nearly 30 million Europeans left their home soil and crossed the Atlantic Sea for the United States. We focus on Sweden, where as many as a quarter of the initial population emigrated. This setting allows us to make use of a wide range of historical data sources covering migration, technological patents and broader measures of technological and economic development. At the onset of its transatlantic migration experience, Sweden was primarily an agrarian economy abundant in low-wage work and labor intensive production processes. During the next decades, Sweden underwent an industrial revolution. While the sources of this development remain disputed among economists and economic historians (eg. Wicksell, 1882; Sandberg, 1979; O’Rourke & Williamson, 1995; Ljungberg, 1996), it is well established that 1In contrast, the effects of immigration on different aspects of economic development have received con- siderable attention. See, eg., Hunt & Gauthier-Loiselle(2010); Borjas & Doran(2012); Hornung(2014); Moser, Voena & Waldinger(2014) for contributions related to the effect on innovation and technology. 2 Swedish real wages went from being below the Western European average in the 1860s to the level of their British counterparts by 1914. Less attention has been paid to the remarkable speed of technological advancements. Described as a technological revolution, this era saw a vast increase in mechanized equipment, which arguably had a profound effect on economic development (Heckscher, 1941). Concurrent with the mass departure of predominantly low- skilled workers, technological patents surged, reaching record high levels at the turn of the century. Shedding some light on the black box of technological progress, this paper asks if and to what extent migration may have played a role in this development. And more broadly, we explore if and how this related to the general economic development of the time. To measure the effects of migration on innovation, we use a novel and hand-collected data set covering the universe of technological patents in Sweden between the mid 19th century and World War I.2 In addition, we collect data on technology adoption in agriculture and industry, as well as incorporated firms and tax revenues. Full-count census data, with individual links over time, are used to track changes in employment across sectors and skill- levels. We combine this with data from church books and shipping line records covering all Swedish migrants over this period, both emigrants and immigrants, to construct a data set at the level of approximately 2,400 municipalities between 1867 and 1914. Our main empirical framework compares long-term changes in economic activity between municipalities within the same region, but with different emigration histories. To obtain exogenous variation in cumulative emigration, we employ an instrumental variable strategy that combines two sources of variation.3 First, it is well-recognized that a series of harvest failures, caused by unusually cold weather, was a crucial push factor for the first wave of large scale migration in the late 1860s (see, eg., Sundb¨arg, 1913; Thomas, 1941; Barton, 1994; Beijbom, 1995). To capture the importance of harvest failures, we use daily temperature data from 1864–1867 to construct a measure of unexpected frost shocks during growing seasons before the onset of mass migration. Second, since there were two main emigration ports – Gothenburg and Malm¨o– we capture the travel cost of emigration using a municipality’s proximity to the nearest emigration port.4 Interacting these two sources of variation, the idea behind the instrument is that negative shocks to agriculture increase emigration especially when the travel costs is low. Because to Swedish migration was highly path dependent (Runblom & Norman, 1976; Beijbom, 1995; Hatton, 1995; Karadja & Prawitz, 2019), which we corroborate, we can strongly predict not only the first wave of migration, but emigration 2We treat technological patents as a proxy for innovation. See, e.g., Griliches(1990); Moser(2005, 2012) for discussions of its limitations. 3The identification strategy is based on Karadja & Prawitz(2019). 4It is well established in the migration literature that travel costs constitute an important part of the migration decision (see, eg., Quigley, 1972; Morten & Oliveira, 2014; Enflo et al., 2014). 3 during the entire mass migration period. By only using the interaction between frost shocks and emigration port proximity as our instrument, we are able to control for the direct effects that these two variables may have by themselves. Therefore, we overcome typical threats to the exclusion restriction that exist when using migration push factors as an instrument. In a balance test, we find that our instrument is not systematically related to baseline characteristics. We also show that a placebo instrument constructed using frost shocks during non-growing seasons does not affect emigration, nor any other of our outcome variables. We document two main sets of results. The first relate to the effect of emigration on the innovation and the adoption of new technologies. We start by showing that emigration caused a long-run increase in technological innovations in sending municipalities. Our preferred IV estimates indicate that a 10 percent increase in the number of emigrants 1867–1900 increases the number of patents 1900–1914 by about 6 percent. The positive effect on patents is, in particular, driven by the upper tails of innovative activity, rather than by municipalities entering into the innovation business. Patents