Plan Your Visit
Agate Fossil Beds National Monument is located in Sioux County in the northwest corner of Nebraska. The Wyoming border is 17 miles to the west, and the South Dakota border 42 miles to the north. The county's only town, its county seat, is Harrison, population 251. The 2,000-square mile county itself has a population of only 1,500 people. Much of the area's land is used for ranching and has a carrying capacity of at least 25 acres for each cow-calf pair.