Fort Boise is either of two different locations in the Western United States, both in southwestern Idaho. The first was a Hudson's Bay Company (HBC) trading post near the Snake River on what is now the Oregon border, dating from the era when Idaho was included in the British fur company's Columbia District. After several rebuilds, the fort was ultimately abandoned in 1854, after it had become part of United States territory following settlement in 1846 of the northern boundary dispute.

Southwestern Idaho is a geographical term for the area along the U.S. state of Idaho's borders with Oregon and Nevada. It includes the populous areas of the Boise metropolitan area and the Treasure Valley.