While many cities near the U.S.-Mexico border have poverty rates above that of the U.S. overall, it is not clear from the available data that the elevated rates can be attributed directly to illegal immigration.

The U.S. Census Bureau does not collect information on whether individuals are in the country legally.

It does, however, track whether people are foreign born and when they entered the country.

Data from 2009 - the most recent year the Census Bureau published Table S0502, which includes breakdowns of the foreign-born population - show that immigrants to Pima County do have a poverty rate above the county rate.

That year, Pima County's foreign-born population had a 31 percent poverty rate, compared with 19 percent for all county residents.

Recent arrivals were more likely to be poor. About 48 percent of those who arrived after 2000 lived in poverty, but only 22 percent of those who arrived before 1990 were in that position.

Foreign-born, married couples with children reported a 31 percent poverty rate, compared with 13 percent for all married families in the county.

Forty-three percent of families led by foreign-born single mothers lived in poverty. For the county overall, the figure was 33 percent.

More recent data, from 2011, show that 22 percent of Pima County children living with a single parent in poverty lived with a parent who was not born in the U.S.

The poverty rate for the foreign-born population was 29 percent, compared with 20 percent overall. Naturalized citizens were less likely to live in poverty, with a rate of 16.7 percent.

Contact reporter Carli Brosseau at 573-4197 or cbrosseau@azstarnet.com. On Twitter: @carlibrosseau