Gallatin County is a county located in the southwest of the state of Montana. The geographical feature that characterizes it is the Gallatin River, which was named in 1805 by Meriwether Lewis in tribute to Albert Gallatin, Secretary of the Treasury of the United States. According to the 2000 census the county population was 67,831, most of them at the county seat, Bozeman, which houses Montana State University. In the southeastern part of Gallatin County there is a small part of the Yellowstone National Park. The Big Sky Resort, one of the largest in the United States, is located halfway between West Yellowstone and Bozeman.