Crosses Dearborn River ID number L25300009+00001 Material Steel, concrete, stone Total length 76 m Bridge type Truss bridge | Maintained by County Highway Agency Design Pratt half-deck truss Opened 1897 Area 4 ha Body of water Dearborn River | |
 | ||
Locale Lewis and Clark County, Montana Location Lewis and Clark County, Montana Similar Rocky Mountains, Canyon Ferry Dam, Montana State Capitol, Holter Dam, Spring Meadow Lake Stat | ||
The Dearborn River High Bridge is a Pratt half-deck truss bridge built in 1897, and has been placed on the National Register of Historic Places as it is one of the few bridges of its type left standing in the United States. On a half-deck bridge, the deck is attached in the center rather than, as is more common, top or bottom of the superstructure. It crosses the Dearborn River on Lake Bean Road (Montana Secondary 435) about 15 miles (24 km) southwest of Augusta, Montana. The unusual design of the Dearborn River High Bridge suits it to carry light loads across high/deep crossings. It has four spans and originally had a wooden plank deck. It is the last standing pin-connected Pratt half-deck truss bridge left in the United States. Construction cost was $9,997. Construction began in 1896 and completed in 1897.
This crossing point on the Dearborn River had been used for many years by the local Indian tribes, primarily the Blackfeet. Prior to the bridge's construction this location was known as the Ponderay Crossing. The river was named for United States Secretary of War Henry Dearborn by Lewis and Clark in 1805. The area was left largely unexplored by Europeans for the next 50 years or so. The bridge was rehabilitated in 2003 by the Montana Department of Transportation, with Sletten Construction of Great Falls, Montana as the lead contractor, and was placed on the National Register of Historic Places on December 18, 2003.