1 vote

Peru Slough Bridge


Photo taken by Steve Conro in December 2011


BH Photo #221663


Original Slough Bridge 

1935 Peru Centennial Information, May 25-26 1935


An iron bridge across the slough, consisting of three fixed spans, each seventy-five feet in length, was begun on July eighteenth,1869 work having been delayed by high water, and completed in November 1869. There was a northern approach 265 feet long, built of timber. The road connecting it with the river bridge was built on an embankment 300 rods long, eight feet high, with a roadbed twenty-five feet wide.

It was thought that this embankment would raise the road above high water level, but it was flooded many times.

This bridge would be replaced by the current bridge in 1917. The old bridge was sold to a local scrap dealer for $100.00.


Pratt through truss bridge over Peru Slough (Illinois River Backwater)
Peru, LaSalle County, Illinois
Open to traffic
Built 1932; rehabilitated 1997
2-span, 7-panel Pratt through truss
Length of largest span: 139.1 ft.
Total length: 286.1 ft.
Deck width: 18.0 ft.
Also called
Illinois River Backwater Bridge
Approximate latitude, longitude
+41.31109, -89.12696   (decimal degrees)
41°18'40" N, 89°07'37" W   (degrees°minutes'seconds")
Approximate UTM coordinates
16/321958/4575474 (zone/easting/northing)
Quadrangle map:
Spring Valley
Average daily traffic (as of 2016)
Inventory number
BH 47631 (Bridgehunter.com ID)
Inspection report (as of August 2018)
Overall condition: Fair
Superstructure condition rating: Satisfactory (6 out of 9)
Substructure condition rating: Satisfactory (6 out of 9)
Deck condition rating: Very Good (8 out of 9)
Sufficiency rating: 80.6 (out of 100)
View more at BridgeReports.com


Built 1932 (962)
Built during 1930s (11,765)
Illinois (4,677)
LaSalle County, Illinois (89)
Open (39,970)
Owned by city (5,443)
Peru, Illinois (6)
Pratt through truss (5,419)
Pratt truss (9,339)
Riveted (2,183)
Span length 125-175 feet (4,234)
Through truss (15,148)
Total length 250-500 feet (5,253)
Truss (32,918)

Update Log 

  • January 12, 2015: Essay added by Gene Smania
  • December 13, 2011: New photos from Steve Conro
  • April 9, 2011: Updated by Matthew Lohry: Corrected bridge type
  • January 11, 2011: Added by J.P.


  • J.P. - wildcatjon2000 [at] gmail [dot] com
  • Matt Lohry
  • Steve Conro - sconro [at] yahoo [dot] com


Peru Slough Bridge
Posted April 9, 2011, by Anthony Dillon (spansaver [at] hotmail [dot] com)

I like how the portal bracing and sway bracing are mirrored throughout the bridge. Puts me in mind of the Indiana Bridge Company and some of their Warren trusses like the Smithfield Bridge: http://bridgehunter.com/in/delaware/1800136/

Ill Rv Back Water Bridge
Posted April 9, 2011, by Matthew Lohry

This bridge's diagonals are very interesting--they're built up, but with solid steel, rather than V-lacing or lattice--much the same way as the built-up panels of a plate girder span.

Ill Rv Back Water Bridge
Posted April 9, 2011, by Gene Smania

Photos were taken in January 2011. Structure was "rebuilt" not "built" in 1997 as bridge plate states. Piers, abutments, and truss steel are original--deck and railing were replaced. It is a two span truss design, not a pony truss.

Ill Rv Back Water Bridge
Posted March 7, 2011, by Gene Smania

These are photos of a previous bridge in the same location. The images are from glass negatives of an unknown date. It crosses the Peru Slough from which ice was harvested in the days before refrigeration. The road it carried crossed the Illinois River at Peru on a wooden swing bridge that was demolished in the 1950's--its south abutment is still there and there is a public boat launch nearby. Sections of the concrete wall along the roadway in the photos are still visible. The local newspaper documents that a new bridge was opened in this location in October 1917, replacing an older bridge. The steel from the old bridge was sold to a local scrap dealer for $100.00