This New York Times article reports the findings of a study by the Center for Immigration Studies. The Center believes that the number of illegal immigrants in the U.S. has dropped by about 1.3 million or roughly 11% in the last year.
The Center attributes the decline to increased enforcement by immigration authorities. Enforcement actions by state and local governments probably have helped too.
Other experts attribute most of the decline to the economic downturn, particularly in the housing industry which employed many illegals as construction laborers. A similar downturn in the travel industry has reduced employment for hotel maids, busboys, and the like.
It is logical to expect the combination of fewer job opportunities and more ICE raids to have a negative effect on illegal immigration. The exact magnitude of the decline is less clear, and I expect their numbers are estimates.
