The district established in 1975 embraces a 15-square mile area and includes property in both Fergus and Chouteau Counties.

The boundary increase area addressed in this nomination lies within Fergus County, and abuts the southeastern side of the original district, including a portion of the Dog Creek drainage and breaks encompassing the site where Ferdinand Hayden uncovered and collected several specimens of fossilized dinosaur bones and teeth in 1855.

"[3] Historic function: Domestic; Transportation; Landscape; Funerary; Defense; Agriculture/subsistence Historic subfunction: Single Dwelling; Fortification; Camp; Graves/burials Criteria: event, event, architecture/engineering, architecture/engineering, person, person, information potential, information potential "A recreation area located between Winifred and Big Sandy, Montana today, this place has a long history of early exploration.

Power, merchant prince of Fort Benton, and John Norris, who managed the ranch for the company.

Today, the recreation area provides a campground and is a common take-out point for many boaters along the Missouri River.