Two groundbreaking studies of illegal immigrants have concluded that while California has far more than any other state -- 2.6 million -- the number has declined slightly as other states become more attractive working and living destinations for border crossers.
The studies were conducted by the Public Policy Institute of California, one a survey of illegal immigration from the national perspective and the other concentrating on California. Both were done by Laura Hill and Hans Johnson and were aimed at creating a factual basis for the often heated debate over the impact of illegal immigration.
The national study concluded that illegal immigrants comprise more than a quarter of the U.S. foreign-born population and slightly less than the entire national population. But the numbers have declined slightly in recent years, due to the shrinkage of employment in what's been termed the "Great Recession" and stepped up border security and immigration law enforcement. The latter has nearly quadrupled deportations since the late 1990s.
The study concluded that the central point of the debate over illegal immigrants - whether they have a positive or negative effect economically - is impossible to resolve because of a lack of hard data on how they affect the economy, and what costs of providing public services may be.
California has been an historic magnet for illegal immigrants, who overwhelmingly come from Latin America. The PPIC research found that its share of the national illegal immigrant population has been shrinking as the flow moves to other states, particularly in the Deep South.
The state's estimated 2.6 million illegal immigrants, the researchers found, are now less than a quarter of the national population estimated to be 11 million. They are, however, about 7 percent of the state's population and 9 percent of its labor force.
"We find that unauthorized immigrants live in every county in the state, primarily but not only in highly agricultural or highly urban areas," Hill and Johnson write. "As in the country as a whole, unauthorized workers here reside not just in traditional immigrant communities, but have found homes throughout all regions of the state."
They drew on hitherto untapped Internal Revenue Service data to make detailed estimates about California's illegal immigrant population. The IRS allows illegal immigrants to file tax returns using "individual taxpayer identification numbers" rather that Social Security numbers. The ITIN data was used to supplement and refine other data.
Using the new methodology, Hill and Johnson pegged the state's illegal population at 2.9 million in 2008 (it's since declined slightly) and did a region-by-region breakdown. While Los Angeles County, the state's largest with nearly 10 million people, also has the state's largest number of illegal immigrants, nearly a million, several rural counties have larger illegal proportions.
Monterey and San Benito counties have the highest concentration at 13.5 percent, the research determined, with Imperial County at 12.8 percent, Napa County at 12 percent and Santa Clara County at 10.2 percent all in double-digits. The smallest illegal populations, proportionately, are in remote mountain counties.