Dearborn River High Bridge

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 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]

Dearborn River High Bridge
Dearborn River High Bridge in May 1980
Coordinates	47°16′52″N 112°23′24″W
Crosses	Dearborn River
Locale	Lewis and Clark County, Montana
Maintained by	County Highway Agency
ID number	L25300009+00001
Characteristics
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]
History
Designer	Zenas King of King Bridge Co., Cleveland, OH
Construction end	1897
Statistics
Daily traffic	100
Dearborn River High Bridge
U.S. National Register of Historic Places
Show map of Montana Show map of the United States
Location	About 15 miles southwest of Augusta, Montana on Bean Lake Road
Coordinates	47°16′52″N 112°23′25″W
Area	9 acres (3.6 ha)
Built	1897, rehab 2003
Architect	King Bridge Co.
Architectural style	Pratt half-deck truss
NRHP reference No.	03001298[2]
Added to NRHP	December 18, 2003

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

• National Register of Historic Places listings in Lewis and Clark County, Montana

References

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). Archived from the original on March 4, 2016. Retrieved January 15, 2012.
4. 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. "MDT Restores Dearborn River High Bridge" (PDF). Montana Department of Transportation. Retrieved January 15, 2012.
6. Kidston, Martin J. (May 11, 2004). "Bridge Over Dearborn River One Of A Kind". Helena Independent Record. Retrieved January 15, 2012.

External links

• Library of Congress photos of the Dearborn River High Bridge
• Dearborn River High Bridge structurae.de
• Dearborn River High Bridge / Lewis and Clark County, Montana bridgehunter.com
• Dearborn River High Bridge in Central Montana bigskyfishing.com