
Back Wall of Chetro Ketl
Chaco Canyon and the Chaco Phenomenon have been studied very intensively for over a hundred years, and the result of much of that research has been to answer a few questions and open up many more. Interpretations have changed quite radically several times over the years, and at many times, including now, there has been an extraordinary diversity of theories proposed to explain Chaco.

Tri-Wall Structure at Pueblo del Arroyo
Wading through all this research is a tall order, especially since much of it is contained in obscure technical reports that are as hard to read as they are to find. It is possible, however, to classify most of it into a few broad schools of thought correlating roughly to different periods of investigation, sites investigated, and people and institutions doing the investigating. This post is an attempt to set up a basic classification of research projects and interpretive theories, mostly as a reference point for future posts to link back to, but also as an introduction for the general reader to the many ways people have approached Chaco over the years. These categories are by no means rigid, and many people appear in more than one, generally at different points in their careers. Many of them also contain a variety of interpretive perspectives, since not everyone working in the same tradition of research necessarily agrees on everything, and there are many scholars who don’t fit well into any particular category and are therefore not included here. Despite these caveats, I hope that this can serve as a useful starting point for understanding who the various researchers are and what background they bring to their publications.
With all that said, here’s the list:
Hyde Exploring Expedition
People: George Pepper, Richard Wetherill
Institutional Support: American Museum of Natural History
Dates of Major Research: 1896–1899
Sites Studied: Pueblo Bonito, some undocumented work at other sites
Theories: Not very theoretically oriented; generally saw sites as precursors of modern pueblos and interpreted findings in that light.
National Geographic Expedition
People: Neil Judd, Frank H. H. Roberts Jr., Anna Shepard
Institutional Support: Smithsonian Institution, National Geographic Society
Dates of Major Research: 1921–1927
Sites Studied: Pueblo Bonito, Pueblo del Arroyo, Shabik’eshchee, a few poorly documented small sites
Theories: Saw two distinct populations at Pueblo Bonito: “Old Bonitians” responsible for Type I masonry and “Late Bonitians” responsible for subsequent masonry types.
Field Schools
People: Edgar Hewett, Clyde Kluckhohn, Paul Reiter, R. Gordon Vivian, Florence Hawley Ellis
Institutional Support: University of New Mexico, Museum of New Mexico, School of American Research
Dates of Major Research: 1920, 1929–1947
Sites Studied: Chetro Ketl, Casa Rinconada, Bc sites, Kin Nahasbas, various other poorly documented sites
Theories: Hewett proposed that the great houses were voluntary communal efforts; Kluckhohn proposed that great houses and small houses were built by different cultural groups at the same time.
Gila Branch
People: Harold Gladwin, Deric O’Bryan
Institutional Support: Gila Pueblo
Dates of Major Research: 1934–1949
Sites Studied: Chetro Ketl, Pueblo Bonito, Pueblo del Arroyo, Peñasco Blanco, Hungo Pavi, Shabik’eshchee, Half House, Pueblo Pintado
Theories: Argued that small house sites (“Hosta Butte Phase”) were precursors of great houses (“Bonito Phase”) and that Ellis and Kluckhohn were wrong to conclude that they were contemporaneous.
Park Service Ruins Stabilization Unit
People: R. Gordon Vivian, Paul Reiter, Tom Mathews, R. Gwinn Vivian
Institutional Support: National Park Service
Dates of Major Research: 1937–1965
Sites Studied: Kin Kletso, Pueblo del Arroyo Tri-Wall Structure, Lizard House, Three-C Site, small stabilization projects at several other sites
Theories: Elaborated on Kluckhohn’s theory that separate ethnic groups simultaneously occupied the great houses (“towns”) and small houses (“villages”) in the canyon; introduced roads and water-control systems into interpretations of Chaco.
Mexicanist School
People: Charles DiPeso, Edwin Ferdon, J. Charles Kelley, Jonathan Reyman, Phil Weigand
Institutional Support: Amerind Foundation
Dates of Major Research: 1955–1993
Sites Studied: Little to no fieldwork in Chaco (considerable fieldwork in Mexico)
Theories: Saw the rise of Chaco as the result of direct action by Mesoamerican actors, perhaps to secure a steady supply of turquoise.
Chaco Project
People: Alden Hayes, Bob Lister, Tom Lyons, W. James Judge, Tom Windes, H. Wolcott Toll, F. Joan Mathien, Peter McKenna, Steve Lekson, Bob Powers, Nancy Akins, David Brugge, Marcia Truell, John Schelberg, Chip Wills
Institutional Support: National Park Service, University of New Mexico
Dates of Major Research: 1969–1982
Sites Studied: Pueblo Alto, many small sites
Theories: Considerable variety of interpretations among project participants; ideas include Chaco as center of regional system of outliers, location for occasional feasting events, headquarters of political hegemon.
Solstice Project
People: Anna Sofaer, Rolf Sinclair, Philip Tuwaletstiwa, Volker Zinser, L. E. Doggett
Institutional Support: National Geodetic Survey
Dates of Major Research: 1977–Present
Sites Studied: Fajada Butte Sun Dagger Petroglyph, Pueblo Bonito, other great houses and petroglyphs
Theories: Focuses on alignments of great houses and petroglyph sites to astronomical phenomena; little emphasis on cultural context, although there have been occasional signs of support for Mexicanist diffusionism.
Chaco Protection Sites Program
People: John Stein, Taft Blackhorse Jr., Rich Friedman
Institutional Support: Navajo Nation Historic Preservation Department
Dates of Major Research: 1997–Present
Sites Studied: Pueblo Bonito, various outlying sites (especially on Navajo Reservation)
Theories: Extensive use of GIS and other digital techniques to create models of Chacoan sites and investigate spatial relationships around and among them; ethnoarchaeological approach incorporating Navajo traditions with implications for cultural continuity that are rather controversial.
Competitive Decentralist School
People: John Kantner, Ruth Van Dyke, Winston Hurst, Dennis Gilpin, David Wilcox
Institutional Support: SAR, Northern Arizona University
Dates of Major Research: 1993–Present
Sites Studied: Focus on outlying sites
Theories: Sees Chaco Phenomenon as less a centralized system based in the canyon than a cultural tradition linking aspiring elites in various politically autonomous communities; details vary.