At a macro level, the 2010 Census appeared to be close to perfect. The Census Bureau reported a net national overcount of 0.01% in 2010, a number not statistically different from zero. Similarly, no state had a statistically significant net undercount, according to Census Bureau estimates. But the apparent precision can be misleading and doesn’t tell the whole story. This Fact Sheet discusses what we know about census accuracy and why it matters to funders and their grantees.