A key challenge facing California in any census is that it is home to high numbers of the populations least likely to participate, including minorities, the young and low-income households. Ten of the top 50 "hard-to-count" counties in the nation are in California, and it has a large population of illegal immigrants, who are less likely to participate in the survey for fear that it would put them on the government's radar. A 2008 study found that the state had more than 5 million hard-to-count residents.
This year, the problem may have been compounded by the fact that the state spent significantly less on census outreach than it did a decade ago, though nonprofit organizations and private foundations tried to fill the gap.
"I don't think any amount of outreach is going to fully eliminate the undercount, particularly in [historically undercounted] communities, some of which are very well represented in California's population," said Thomas A. Saenz, president and general counsel of the Mexican American Legal Defense and Educational Fund.
The organization and others tried to reassure Latino immigrants that participating in the census was "safe, important and simple. But the emphasis was on the first, the safety."