IDAHO, a territory of the United States, part of the Louisiana cession. (See ANNEXATIONS, I) It was originally a part of the territory of Oregon, was then transferred to the territory of Washington, and was organized as a separate territory, March 3, 1863. As first organized it covered 326,373 square miles; but, since then, the whole territory of Montana, and nearly the whole territory of Wyoming, have been taken from it. It now comprises 86,294 square miles, lying between Washington territory and Oregon on the west, Montana and Wyoming on the east, British Columbia on the north, and Utah and Nevada on the south. Its population in 1880 was 32,610. The capital is Boise City, and the governor John B. Neil.
—The act of March 3, 1863, is in 12 Stat. at Large, 808.