Fort Peck, Montana- Fort Peck Dam & Charles M. Russell National Wildlife Refuge.

The World Almanac lists Fort Peck Dam as the largest embankment dam in the United States with the fifth largest man-made reservoir. Fort Peck Dam was completed in 1937 and contains 1.25 billion cubic yards of earth, and extends four miles. Tours are offered from June – September.  
Of Special interest: Tyrannosaurus rex skeleton was discovered at Fort Peck. 

CMR is a 1.1 million acre refuge that contains native prairies, forested coulees, river bottoms, badlands and the 250,000 acre Fort Peck Reservoir, as well as the Missouri Breaks wilderness region. Refuge wildlife include mule and white-tailed deer, elk, bighorn sheep, antelope, coyote, bobcat, beaver, sharp-tailed grouse, numerous other species