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| Name | Jay Cooke State Park Railroad Bridge Northern Pacific Railway Bridge #131 |
| Built By | Northern Pacific Railway |
| Currently Owned By | Minnesota Department of Natural Resources |
| Superstructure Contractor | American Bridge Company of New York |
| Substructure Contractor | J.J. Elliott & Company of St. Paul, Minnesota |
| Length | 155 Feet Total |
| Width | 1 Track |
| Height Above Ground | 64 Feet |
| Superstructure Design | Pratt Through Truss |
| Substructure Design | Stone Masonry and Concrete |
| Date Built | 1906 |
| Traffic Count | 0 Trains/Day (Bridge is a Trail) |
| Current Status | Open to Trail Traffic |
| Northern Pacific Railway Bridge Number | 131 |
| Significance | Moderate Significance |
| Documentation Date | 2/8/2014; 4/18/2015 |
In 1867, the Lake Superior and Mississippi Railroad (LS&M) began construction on a new railroad line, extending north from St. Paul, Minnesota to Duluth, Minnesota; a distance of 155 miles. The LS&M was sold to the St. Paul and Duluth Railroad (StP&D) in 1877. Known as the "Skally Line", the line became a principal connection between the Twin Ports of Duluth, Minnesota and Superior, Wisconsin. A major line change was completed in 1888, when the "Duluth Short Line" was constructed between Thomson and Duluth, and the original line reduced to a spur. The StP&D would be sold to the Northern Pacific Railway (NP) in 1900. NP operated this as their mainline between the Twin Cities and the Twin Ports. NP had a large network of railroad lines in Minnesota, and also had a network that extended to the Pacific Coast at Seattle.
In 1970, NP would merge with rival Great Northern Railway (GN) and the Chicago, Burlington & Quincy to form Burlington Northern Railroad (BN). The GN had a parallel route, and BN quickly began to favor that route. The first section abandoned was between Carlton and West Duluth in 1976. Further cuts came in 1977, when the segment between Hinckley and Moose Lake was abandoned. By 1980, the Moose Lake to Carlton segment would be abandoned. The segment between Hugo and Forest Lake would be abandoned 1987, and the segments from Forest Lake to North Branch and White Bear Lake to St. Paul abandoned in 1989. All of the abandoned segments would be acquired for recreational trail use. In 1996, BN merged with the Atchison, Topeka & Santa Fe Railway to form BNSF Railway. In 1997, BNSF would sell the Hinckley-North Branch segment to the St. Croix Valley Railroad (SCXY).
Today, the Minnesota Commercial operates a small segment from Hugo to I-694 and SCXY continues to operate the Hinckley-North branch segment. The Bruce Vento Trail utilizes the former railroad grade between St. Paul and I-694, while the Sunrise Prairie Trail utilizes the grade between Hugo and North Branch, and the Willard Munger State Trail utilizes the railroad between Hinckley and West Duluth. BNSF continues to operate small amounts of track in Duluth.
Located between Carlton and Thomson, this through truss bridge carries the former Northern Pacific Railway over the St. Louis River. The first bridge over the St. Louis River was located downstream, and initially consisted of a wooden through truss bridge, which was replaced by a combination Howe through truss bridge in 1877. Due to the extreme grades and curves along the original line, a new cutoff was constructed through Thomson in 1888. At this time, a new 155-foot Whipple through truss bridge was installed over the St. Louis River at this location. The truss was fabricated by an unknown company, and the stonework was completed by J.J. Elliott & Company. Bridging the river at this location was difficult, due to the jagged cliffs and dalles in the river. By the early 20th Century, the bridge had become too light for traffic, and would be replaced by the present through truss bridge.
Currently, the bridge consists of a 155-foot, 6-panel, pin-connected Pratt through truss span, set onto stone and concrete abutments. Both stone abutments from the previous bridge were reused, and a concrete extension was added to the west abutment. The truss span uses a standard NP design, with heavily constructed members, a standard floor and the standard NP portal design. American Bridge Company fabricated the superstructure, while company forces completed the concrete additions to the west abutment. The Pratt truss design was arguably the most commonly used railroad truss design in the second hand of the 19th Century, as it was durable, strong, economical and simple. Pin connected spans eventually became obsolete with the introduction of riveted spans. After the railroad was abandoned, the bridge and railroad were converted to the popular Willard Munger State Trail. This bridge appears to be in good condition, and should be able to serve the trail for years to come. The author has ranked this bridge as being moderately significant, due to the common design.
Citations
| Builder and build date | Builders Plaque |
| Superstructure builder | Pre-Valuation Report digitized by the Northern Pacific Railway Historical Association Archives |
| Builders Plaque | |
| Railroad History Citation | ICC Valuation Information, Compiled by Richard S. Steele |