The Department of Alaska was the governmental designation of Alaska from its purchase by America in 1867 until its organization as the District of Alaska in 1884. During the Department era, Alaska was variously under the jurisdiction of the U.S. Army (until 1877), the United States Department of the Treasury (from 1877 until 1879) and the U.S. Navy (from 1879 until 1884).
The area later became the Alaska Territory, then Alaska.
