The United States has about 11.3 million undocumented immigrants. But how many of them are living in Virginia? “At the national level, ballpark estimates are credible.” That’s Qian Cai at the University of Virginia, who says she's often asked to give a ballpark estimate for undocumented immigrants in Virginia. “But the smaller the geography gets to, even at the state level, the margin of error gets to be quite large. And that’s why it’s not often produced or cited at the state level for illegal immigration statistics.”