According to the U.S. Census Bureau, the county has a total area of 2,370 square miles (6,100 km2), of which, 2,356 square miles (6,100 km2) of it is land and 14 square miles (36 km2) of it (0.59%) is water. Over 74 percent of the county’s land area lies within the Fort Peck Indian Reservation.
In May of 1805, the Lewis & Clark expedition camped on the Missouri River south of the present day Wolf Point. The Welcome to Wolf Point and Culbertson web sites have lots of local information and links to area attractions. Fort Buford and Fort Union are located on the Missouri River at the SE corner of Roosevelt County and North Dakota.