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Military Street Bridge (1913)


West Elevation, Looking Southeast

The vertical truss appears to be a component of this bridge, but is an optical illusion. It is not a component of this bridge but is a railroad bridge downriver.

Photo taken by Carla Anderson, June 1990, for HAER

View photos at Library of Congress

BH Photo #120613

Street View 


Lost Bascule Bridge over Black River on I-94/I-69 Business Loop (ex-US 25, ex-M-25) in Port Huron
Port Huron, St. Clair County, Michigan
Replaced by new bridge
Built 1912-13; Replaced 1991
- Detroit Steel & Bridge Co. of River Rouge, Michigan
- McKenzie Bridge Co.
- Osborn Engineering Co. of Cleveland, Ohio
- Strauss Bascule Bridge Co. of Chicago, Illinois
"The Military Street Bridge is [was] the oldest surviving bascule highway bridge in Michigan and is an excellent example of the underneath counterweight trunnion design developed by Jospeh B. Strauss, an important twentieth century American bridge engineer.

"The Military Street Bridge is a double-leaf bascule bridge of the Strauss trunion type, with counterweights and the operating machinery located beneath the deck.

"Each leaf consists of three parallel steel girders, placed 13 feet apart, center to center, surrounded by a steel framework, 65 feet wide and 54 feet long, which in turn, supports the roadway and sidewalks."

--Dr. Charles K. Hyde, Department of History
Wayne State University
for Federal Highway Administration, Michigan DOT and HAER
June 1990
Length of largest span: 54.0 ft.
Total length: 108.0 ft.
Deck width: 65.0 ft.
Also called
I-94/I-69 Business Loop Bridge
Approximate latitude, longitude
+42.97556, -82.42417   (decimal degrees)
42°58'32" N, 82°25'27" W   (degrees°minutes'seconds")
Approximate UTM coordinates
17/383871/4759084 (zone/easting/northing)
Quadrangle map:
Port Huron
Inventory number
BH 37124 (Bridgehunter.com ID)

Update Log 

  • September 26, 2013: New Street View added by Douglas Butler
  • August 10, 2008: Added by J.R. Manning

Related Bridges 


  • J.R. Manning - thekitchenguy [at] sbcglobal [dot] net
  • HAER MI-38 - Military Street Bridge, Spanning Black River at Military Street, Port Huron, St. Clair County, MI
  • Historicbridges.org - by Nathan Holth
  • Douglas Butler


Military Street Bascule Bridge (Old)
Posted December 23, 2019, by Mike Kerkau (mjkerkau [at] gmail [dot] com)

It should be noted that Military Street has history with multiple highways.

At the inception of Michigan's trunkline system, this route originally served as Trunk Line 31. (There is no corresponding "M-31" today, probably due to the existence of US 31.) https://img.lib.msu.edu/exhibits/map/MIRoadMaps/1919-lp.jpg

In 1926, M-29 is relocated to Port Huron and replaces M-31.

In 1933, M-29 is replaced in Port Huron with US 25. http://www.michiganhighways.org/listings/M-029.html

In 1963-64, US 25 is relocated to run concurrently with I-94, and this route becomes Business US 25. http://www.michiganhighways.org/listings/HistoricUS-025pg2.h...

Between September 26, 1973, and February 28, 1974, US 25 is de-commissioned in Michigan, with the Business Route becoming an extension of M-25.

Finally, in 1987, M-25 is scaled back to end where it does today, with Business Loops I-69 + I-94 taking its place here. http://www.michiganhighways.org/listings/M-025.html

So...yeah. This only served the Business Loops of 69 & 94 for its last four/five years before its replacement, and those were the SIXTH (!) different highway designation for this road.