How large is the national American Indian and Alaska Native population?

According to the U.S. Bureau of the Census, the estimated population of American Indians and Alaska Natives, including those of more than one race, as of July 1, 2007, was 4.5 million, or 1.5 per cent of the total U.S. population.  In the BIA’s 2005 American Indian Population and Labor Force Report, the latest available, the total number of enrolled members of the (then) 561 federally recognized tribes was shown to be less than half the Census number, or 1,978,099.