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**Social costs in** **_destination_ areas.** Internationally, host countries benefit substantially from migration.  Migrants replenish the labor supply (at both ends of the skill spectrum),<sup>34</sup> they spur entrepreneurship and innovation and ease fiscal strains on the pension system (UNDP, 2009; World Bank, 2016b).  Domestically, to the extent that population density (urbanization) comes along with agglomeration economies, it also fosters economic growth and employment generation, translating into economic density (Duranton, 2014).

In general, the net impact of migration on receiving labor markets seems to be small but this does not preclude that some workers can be negatively affected, at least during an adjustment period. A recent meta-analysis of seven studies, all of high-income countries, shows that increasing the share of immigrants 1 percentage point in a local labor market results in declines in native employment of just 0.011 percent and in native wages of 0.029 percent (Longhi, Nijkamp, and Poot, 2010). Docquier, Özden, and Peri (2014) provide estimates of the impact of immigration on wages and employment in OECD countries in the 1990s. They find positive, but small, impacts across countries on both less-educated and all locals even using pessimistic scenarios. Nonetheless, it is important to recognize that there can be transition costs as labor markets adjust and new investments, innovation, and job opportunities materialize. Behind average effects, there can be groups of workers (e.g., older and less educated workers, or semi-skilled workers in certain occupations) that might lose jobs to competition, face longer unemployment spells, or see a decline in their earnings. Recent work in Malaysia suggests that immigration increases employment overall but may have a negative impact on the employment of less-educated locals (del Carpio et al. 2015). In Thailand, negative wage impacts from doubling the size of the immigrant workforce in a province are isolated to less-skilled native workers.<sup>35</sup> Congestion of public services and fiscal costs of social services are also frequently cited in policy discussions. Net fiscal impacts of migrants tend to be slightly positive, but the effects on social services depend on the rights and access granted. Research for OECD countries finds, not surprisingly, that impacts are more favorable when labor migration dominates, when immigrants have higher employment rates, and when immigrant populations are relatively young (OECD 2013). This is because younger migrants tend to be healthier and use fewer services while employed migrants tend to use fewer services and contribute more in taxes and social security.

The effect of migration on crime depends, in part, on labor market outcomes. In general, fears that immigrants are disproportionately more involved in criminal activities than natives do not seem to be justified by the existing literature; on the contrary immigration has often led to a reduction in crime. For instance, recent research from Malaysia finds that immigrants reduce crime (Özden, Testaverde, and Wagner, 2018). These results are in line with international 34 By way of example, migrants make up 16 percent of the U.S. labor force, but are concentrated in certain sectors. They make up most farm workers and 60 percent of construction related occupations. At the other end of the spectrum, one-third of physical scientists, engineering professors and doctors are also foreign born.

35 And even that is not always easy to establish robustly (Pritchett, 2017). Insights from three country case studies (of Kenya, Tanzania and Uganda) suggest that the local economy often benefits from the influx of refugees, through increased demand for local goods and services and better connectivity following investment in new roads and transport services to reach the camps (Verwimp and Maystadt, 2015). But not everyone benefits. The landless and agricultural workers, whom refugees may compete with on the labor market, and net food buyers suffer, at least in the short run.