The population of undocumented residents in the United States increased by about 23 percent .. in the four-year period ending last March ..The original Pew Hispanic Center report is available here. The Pew organizations are partisan leftwing outfits, so consume with a salt shaker close at hand. Posted by Greg RansomOverall, the U.S. foreign-born population, regardless of legal status, was 35.7 million last year. Those of Mexican descent again comprised the largest group - more than 11 million, or 32 percent .. The number of U.S. residents with Mexican backgrounds has increased by nearly 600,000 annually since 2000 ..