Final answer:
According to Census 2000, 4 out of 10 American Indians lived in the Southwest, particularly in New Mexico and Arizona, where federally recognized tribes and traditional communities are significant.
Step-by-step explanation:
According to Census 2000, 4 out of 10 American Indians lived in the area known as the Southwest, particularly in states like New Mexico and Arizona. This region has a significant Native American presence with the Navajo tribe being the largest in the United States. The Southwest is known for having twenty-one federally recognized tribes, and the reservations and traditional communities occupy more than one-fourth of Arizona's land, which correlates with the living situation of many Native Americans as described by the census data.