 According to the U.S. Census Bureau, the county has a total area of , of which is land and (0.7%) is water.Boundary County Airport is a county-owned, public-use airport located two nautical miles (3.7 km) northeast of the central business district of Bonners Ferry.As of the census of 2000, there were 9,871 people, 3,707 households, and 2,698 families living in the county.