Depositional period during which time the paleo-channel was filling. There is some historical, anecdotal evidence that the inhabitants of Chaco Canyon may have constructed a dam at the west end of the canyon.
Pueblo Bonito is four stories tall and contains 800 rooms 
Fifty-year drought in the Southwest. Rain and snow cease to fall. Alluvial groundwater declines, floodplain erosion occurs. Dry-farming zone reduced, crop production potential decreased. Severe arroyo cutting and depression of alluvial groundwater. Severe environmental stress.
Collapse of the Ancestral Puebloan culture at Chaco Canyon.
Josiah Gregg refers to the Chaco pueblos in his book Commerce of the Prairies, making its first appearance in popular culture.
Lt. James H. Simpson leads the Washington Expedition, a military reconnaissance team which surveys Navajo lands and records cultural sites in Chaco Canyon. Illustrations created by the Kern brothers are included in a government report.
Artist and photographer William Henry Jackson participates in the Hayden Survey of the Western United States, producing maps of Chaco Canyon, but no photographs due to technical problems.
General Land Office special agent S. J. Holsinger recommends creating a national park to preserve archaeological sites in Chaco Canyon
Chaco Canyon National Monument is established.
American astronomer and University of Arizona professor A. E. Douglass participates in a National Geographic Society research project exploring Chaco Canyon. Using his newly invented technique of dendrochronology, Douglass dates Chetro Ketl and dozens of Chacoan sites
Expedition under Neil Merton Judd to collect dendrochronological specimens to date habitation of Chaco Canyon
Fourteen rooms at Pueblo Alto excavated by the Chaco Project
Chaco Canyon National Monument is renamed Chaco Culture National Historical Park with 13,000 acres (53 km²) added. The Chaco Culture Archaeological Protection Site program is created to protect Chacoan sites.
NASA's Thermal Infrared Multispectral Scanner (TIMS) detects over 200 miles of a prehistoric (AD 900 or 1000) road system in Chaco Canyon, as well as walls, buildings, and agricultural fields.
Dean and Warren estimate 200,000 trees were used to build great houses.