A study recently released by the RAND Corporation shows that fewer Mexican immigrants returned home from the United States during 2008 and 2009 than in the two years prior to the start of the recession. It's an interesting finding that suggests that — despite a marked downturn in illegal crossings from Mexico — illegal immigrants already in the U.S. are not going home in droves.

This explanation comes from a news release about the report:

"The recession in the United States and the global financial crisis did not increase the number of immigrants returning to Mexico," said Michael Rendall, the study's lead author and director of the RAND Population Research Center. "Migration in both directions between the United States and Mexico slowed during the recession, but our findings show there was no rush by Mexican immigrants to return home."

Researchers found that the findings are consistent with past studies about migration patterns between Mexico and the United States during the U.S. recessions of the early 1970s, 1980s and 1990s.

One possible explanation, researchers suggest, is the "target earner hypothesis," which refers to the theory that immigrants return home when they reach a savings goal.

"This theory suggests that immigrants stay in the United States until they have achieved a certain levels of savings, even if they face a period when their earnings drop and employment becomes harder to find," Rendall said in the press release. 

The study is based on information collected by Mexico's National Survey of Occupation and Employment, a quarterly survey of 100,000 households that asks a wide variety of questions about family members, including whether there are new members who were in another country during the previous quarter.