provides a succinct description of the so-called Second Great Migration including information about the historical context, the structure of immigrant flows by country of origin, and the most salient measures taken by the US immigration regulators in order to shape migration according to their policy objectives.

A wide scale phenomenon influenced by complex factors and having equally complex implications, the US immigration story became the topic of a very rich economic literature attempting to answer the endless list of questions posed by migration researchers. In what follows I will focus on the part related to the performance of male immigrants<sup>3</sup> and the determinants of their performance. Extensive surveys of the existing literature are available in Borjas (1994) and LaLonde and Topel (1997).

The research focusing on immigrants’ assimilation is an arena of strong debates. One explanation for the lack of consensus on many topics in the literature can be found in the quality of data. No single source provides comprehensive information on immigrants, therefore authors compensate by imposing various assumptions and implementing different methodologies which often lead to conclusions that significantly differ from each other. The US Census, although most widely used<sup>4</sup> because of the richness in information, fails to distinguish between legal and illegal immigrants, doesn’t account for return migration, and formulates questions essential for migration research ambiguously. To benefit from yearly flows of data, some authors use instead the Current Population Survey (CPS), while warning readers about the little reliability of their small sample-based estimates.<sup>5</sup> Alternatively, Immigration and Naturalization Service statistics are more accurate with respect to indicators of legal status, but fail to provide a clear picture of the individual ones, such as immigrants’ income.<sup>6</sup> Longitudinal studies, although most conducive to comprehensive research, have often a restricted coverage,<sup>7</sup> so their conclusions are hard to generalize. To increase estimates’ accuracy, other researchers combine data from various cross-

> 3 Typically, migration studies tend to cover either men or women.  This is due to the fact that analyses of female migration require the additional consideration of the specific selection bias arising from women’s decision to participate on the labor market.  Methodological differences aside, female migration research, although more restraint than research on men migration follows a parallel trajectory both in a temporal sense and with respect to the empirical strategy (Ex. Long (1980) applies for women migration the approach in Chiswick (1978), Schoeni (1997) and Schoeni (1998) follow similar strategies, the first paper with respect to men immigrants, and the second with respect to female immigrants). 4 Chiswich (1978), Borjas (1985, 1987, 1994, 1995), Lalonde and Topel (1990), Duleep and Regets (1994) to name just very few who relied on census data.

> 5 Funkhouser and Trejo (1995)

> 6 Jasso and Rosenzweig (1986), Chiswick (1986) Jasso et al (2000)

> 7 For example, focus on one type of occupation, as in Borjas (1989).

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