 By 1851 , treaties between Native American tribes and the U.S. government had opened much of Minnesota to settlement , so Fort Snelling no longer was a frontier outpost . It served as a training center for soldiers during the American Civil War and later as the headquarters for the Department of Dakota . A portion has been designated as Fort Snelling National Cemetery where over 160 @,@ 000 are interred . During World War II , the fort served as a training center for nearly 300 @,@ 000 inductees . After World War II , the fort was threatened with demolition due to the building of freeways Highway 5 and Highway 55 , but citizens rallied to save it . Fort Snelling is now a historic site operated by the Minnesota Historical Society . 
