The Chaco Meridian is a theoretical north-south axis on which lie the Ancestral Puebloan sites, Aztec Ruins and Chaco Canyon, as well as Paquime at Casas Grandes in northern Mexico. Archeologist Stephen H. Lekson developed the theory, which suggests the location of these sites on the same approximate line of longitude (107°57'25") was intentional, and represents a ceremonial connection between them. In 2009 in Archeology Magazine, he amended the list of sites on the "meridian" to include Shabik’eschee, which is south of Chaco, and Sacred Ridge near Durango, Colorado.