Native Americans have been undercounted in two of the last three U.S. census totals, conducted every ten years. The Census Bureau determined that it undercounted Native Americans living on reservations by 4.9% in 2010, slightly overcounted that group in 2000 and undercounted them by 12.2% in 1990.
According to the Carsey School of Public Policy at the University of New Hampshire, there are 12 "hard-to-count" rural counties that are majority Native American. Defining characteristics of such areas include homes without land lines, persons living below the poverty level, and high unemployment rates.