Immigration and welfare magnets.

"This paper investigates if the location choices made by immigrants when they arrive in the United States are influenced by the interstate dispersion in welfare benefits. Income-maximizing behavior implies that foreign-born welfare recipients unlike their native-born counterparts, may be clustered in the states that offer the highest benefits. The empirical analysis indicates that immigrant welfare recipients are indeed more heavily clustered in high-benefit states than the immigrants who do not receive welfare, or than natives. As a result, the welfare participation rate of immigrants is much more sensitive to changes in welfare benefits than that of natives."
(excerpt)