The heading “Chaco Area” refers to the region of the United States containing resources related to the prehistoric Chacoan culture. This area includes Chaco Culture National Historical Park—which encompasses Chaco Canyon and three outlying sites—and the San Juan Basin, a large geologic formation in the four-corners area of Arizona, Utah, Colorado, and New Mexico which contains additional Chacoan outlying sites. This subseries consists of project material on archeological studies, aerial mapping projects, and other remote sensing activities conducted in the park and the surrounding basin region.