text: Study: Illegal immigration has slowed considerably | Idaho Statesman
  But this still marks an improvement over the period between 2005 and 2007, when an estimated 550,000 illegal immigrants entered annually. Possibly because of tighter enforcement measures and economic circumstances driving some immigrants back home, the total population is down from its estimated 2007 peak of 12 million.
  "Particularly along the Southern border, enforcement has ramped up considerably," Passel noted. "It's harder and more dangerous for immigrants to cross into the country."
  Illegal immigrants still remain concentrated in a relatively few states. An estimated 2.5 million illegal immigrants live in California, 1.6 million live in Texas and 675,000 live in Florida.
  California's illegal immigrant population is down an estimated 3 percent from 2005, while Florida's fell a far more dramatic 27 percent. In Texas, the illegal immigrant population actually increased slightly.
  The researchers caution that their findings based on sampling are subject to a margin of error, as well as the inherent uncertainties in tracking an illegal population. Consequently, the overall illegal immigrant population estimates are described as "not conclusive."
  Still, parts of the 37-page study released Wednesday track some other studies, including a Department of Homeland Security assessment that the number of illegal immigrants fell from 11.8 million in 2007 to 10.8 million in 2009. The researchers used different Census Bureau data for their respective studies.
  The Pew Hispanic Center study also arrives at a politically opportune time, as state and federal lawmakers debate immigration reform and border security measures. The Obama administration is challenging a new Arizona law that requires police to check identification papers of suspected illegal immigrants, while Congress considers new legislation.
  "Our borders are just too vast for us to be able to solve the problem only with fences and border patrols," President Barack Obama said in July, adding that "stopping illegal immigration must go hand in hand with reforming our creaky system of legal immigration."