Dearborn River High Bridge

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Dearborn River High Bridge
Dearborn River High Bridge kleiner.jpg
Dearborn River High Bridge in May 1980
Crosses Dearborn River
Locale Lewis and Clark County, Montana
Maintained by County Highway Agency
ID number L25300009+00001
Designer Zenas King of King Bridge Co., Cleveland, OH
Design Pratt half-deck truss
Material Steel, concrete, stone
Total length 251 feet (77 m)
Width 16.1 feet (4.9 m)
Height 100 feet (30 m)
Longest span 160.1 feet (48.8 m)[1]
Construction end 1897
Daily traffic 100
Dearborn River High Bridge
Dearborn River High Bridge is located in Montana
Dearborn River High Bridge
Location About 15 miles southwest of Augusta, Montana on Bean Lake Road
Coordinates 47°16′52″N 112°23′25″W / 47.28111°N 112.39028°W / 47.28111; -112.39028Coordinates: 47°16′52″N 112°23′25″W / 47.28111°N 112.39028°W / 47.28111; -112.39028
Area 9 acres (3.6 ha)
Built 1897, rehab 2003
Architect King Bridge Co.
Architectural style Pratt half-deck truss
Governing body County Highway Agency
NRHP Reference # 03001298[2]
Added to NRHP December 18, 2003

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.[3] It is the last standing pin-connected Pratt half-deck truss bridge left in the United States.[4][5] Construction cost was $9,997. Construction began in 1896 and completed in 1897.[6]

This crossing point on the Dearborn River had been used for many years by the local Indian tribes, primarily the Blackfeet.[5] Prior to the bridge's construction this location was known as the Ponderay Crossing.[6] 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.[4] 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.[5]

See also[edit]


  1. ^ "Dearborn River High Bridge". Bridge Hunter. Retrieved January 15, 2012. 
  2. ^ "National Register Information System". National Register of Historic Places. National Park Service. July 9, 2010. 
  3. ^ "The Dearborn Bridge". Montana Education Telecommunications Network (METNET). Retrieved January 15, 2012. 
  4. ^ a b Jon Axline, ed. (2008). Montana's Historical Highway Markers (4 ed.). Helena, MT: Montana Historical Society Press. p. 97. ISBN 0-9759196-4-4. Retrieved January 15, 2012. 
  5. ^ a b c "MDT Restores Dearborn River High Bridge" (PDF). Montana Department of Transportation. Retrieved January 15, 2012. 
  6. ^ a b Kidston, Martin J. (May 11, 2004). "Bridge Over Dearborn River One Of A Kind". Helena Independent Record. Retrieved January 15, 2012. 

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