Cross Ranch State Park and the surrounding area are living textbooks on cultural history. The park and nature preserve are listed on the National Register of Historic Places as an archeological district.
The Mandan Indians predominated the area's cultural history. Mandan village sites have been found within the park and preserve, ranging from villages of rectilinear lodges the Mandan are thought to have built in the 12th century, to the round earth lodges Lewis and Clark noted on their journey upriver in 1804.
By the late 1700s, the fortified Mandan villages were major trading centers. Several hundred people occupied each. A stable lifestyle and abundant resources allowed the Mandan to develop a rich and intricate culture. Unfortunately, it could not protect them from the diseases that came with the white man, and a series of smallpox epidemics in the late 1700s and early 1800s took their toll. Today, descendents of the Mandan live on the Fort Berthold Indian Reservation around Lake Sakakawea.
In October of 1804, the Lewis and Clark Expedition camped across the river from the park. Meriwether Lewis wrote of the “handsome hight prairie.” Just a few miles upstream, northwest of present day Washburn, the expedition made its winter camp at Fort Mandan. The natural diversity noted in the expedition's journals can still be found in the thousands of acres on the preserve and in the state park.
In 1879, A.D. Gaines, a professor of classical literature, came to the area as a land agent for the Northern Pacific Railroad, eventually purchasing over 11,000 acres. During his time at the ranch Gaines, a Teddy Roosevelt enthusiast, acquired the Maltese cross brand. The nearby town of Sanger was also established during that time. Once a thriving town with a railroad depot and steamboat service, the town was short lived. After the Depression several businesses closed. Due to improved roadways and automobiles, people traveled further for their goods and the town slowly died. The post office was the last business to close. All that remains today are a handful of abandoned buildings.
In 1956, ownership of the Gaines Ranch passes to Bob and Gladys Levis, who renamed their land Cross Ranch. The Nature Conservancy subsequently purchased the ranch in the 1980s. Both the Conservancy and Burlington Northern Railroad donated land to create Cross Ranch State Park. The Nature Conservancy manages the remaining neighboring land, some 6,000 acres, as a dedicated state nature preserve. Hiking trails now connect the park and preserve.