City (pop., 2000: 185,787), capital of Idaho, U.S. The largest city in the state, it lies on the Boise River. Following the 1862 gold rush to the river basin, Fort Boise was established in 1863, and a community developed to provide services for the mines. It became the capital of Idaho Territory in 1864, and of the state in 1890. Agricultural expansion and the growth of the lumber industry contributed to its rapid growth. Boise is the headquarters of the Boise National Forest.