 Air defense units within the Continental United States (CONUS) were given to the Eastern and Western Air Defense Liaison Groups, with Western and Eastern Air Defense Forces activated on 1 September 1949.The command was originally assigned the region within the Continental United States (CONUS) to the west of the 102d degree of longitude, from the Canada–US border in the north to the Rio Grande border between the United States and Mexico in the south and west to the Pacific Ocean coastline.This was adjusted in 1951 with the activation of Central Air Defense Force (CADF) with the region being adjusted slightly to the west to the border of Montana and North Dakota at the Canada–US border, south along the eastern borders of Montana, Wyoming, Colorado and New Mexico to the Mexico–US border.