Pocatello is the county seat and largest city of Bannock County, with a small portion on the Fort Hall Indian Reservation in neighboring Power County, in the southeastern part of the U.S. state of Idaho. It is the principal city of the Pocatello metropolitan area, which encompasses all of Bannock and Power counties. As of the 2000 census the population of Pocatello was 51,466 with a metro population of 83,303. Pocatello is the fourth-largest city in the state, slightly larger than Idaho Falls. In 2007, Pocatello was ranked twentieth on Forbes list of Best Small Places for Business and Careers. Pocatello is the home of Idaho State University and the manufacturing facility of ON Semiconductor. Founded as an important stop on the first railroad in Idaho during the gold rush, the city later became an important center for agriculture. It is located along the Portneuf River where it emerges from the mountains onto the Snake River Plain, along the route of the Oregon Trail. The city is named after Chief Pocatello, a chief of the Shoshoni tribe who granted the right-of-way for the railroad across the Fort Hall Indian Reservation. The city is served by the Pocatello Regional Airport.