The command was activated on 25 October 1948, being the first Air Division for air defense. Its headquarters was at Silver Lake, near Everett, Washington under Continental Air Forces (ConAC). The 25th AD did not assume any command responsibilities until 1949 when it became an intermediate level command under the Air Defense Command, Western Air Defense Force. Its initial Area of Responsibility (AOR) was a large area of the northwest Continental United States, from the 103rd meridian west and north of the 42nd parallel north. This encompassed an area consisting of the states of Washington, Oregon, Idaho, Montana and Wyoming and the western parts of North and South Dakota as well as Nebraska.