Legal versus illegal U.S. immigration and source country characteristics.

"Based on micro data from the Immigration and Naturalization Service (INS) on legal immigrants as well as on legalization applications that followed the passage of IRCA [the Immigration Reform and Control Act of 1986], this study exploits the variation in legal and illegal immigration flows across seventy source countries to examine the sensitivity of immigration flows to underlying source country characteristics. The study finds that earnings in the source country and the distance from the United States form significant deterrents of both legal and illegal immigration flows. We also find that illegal immigration is more sensitive to such factors than is legal immigration." The impact of the North American Free Trade Agreement on U.S. immigration from Mexico is also assessed.