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| Name | Seventh Street Improvement Arches |
| Built By | Northern Pacific Railway |
| Currently Owned By | City of St. Paul |
| Superstructure Contractor | McArthur Brothers of Chicago, Illinois |
| Substructure Contractor | Michael O'Brien of St. Paul, Minnesota |
| Engineer | William Albert Truesdell |
| Length | 125 Feet Total, 41 Foot Largest Span |
| Width | 124 Feet |
| Height Above Ground | 20 Feet (Estimated) |
| Superstructure Design | Helicoidal Stone Arch |
| Substructure Design | Stone Masonry |
| Date Built | 1884 |
| Traffic Count | 19,398 Vehicles Per Day (2019) |
| Current Status | Open to Traffic |
| Significance | High Significance |
| Documentation Date | 7/8/2015; 8/26/2015 |
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.
View the MNDOT page for this historic bridge
Located at the south end of Swede Hollow, this stone arch bridge carries East Seventh Street across the former Northern Pacific Railway, now the Bruce Vento Nature Trail. In February 1883, funding was allocated for the construction of significant improvements on Seventh Street east of downtown St. Paul. As part of the work, a stone viaduct would be constructed across the St. Paul and Duluth Railroad tracks. The design chosen consisted of two helicoidal stone arch spans, with a width of 124 feet. The bridge was designed by William Albert Truesdell, the city engineer of St. Paul. Because of how 7th street crossed the railroad, the bridge required a 20-degree skew. A helicoidal arch uses precision masonry to create a skewed arch. This style of stone arch is exceptionally rare in the United States, with only a handful of examples known.
Construction on the bridge began in September 1883, with Michael O'Brien of St. Paul, Minnesota serving as contractor for the excavation, foundation and abutments. Stone for this work was quarried locally, typical of early stonework in St. Paul. McArthur Brothers of Chicago, Illinois completed the arches using limestone quarried at Kasota, Minnesota. The bridge opened to traffic in December 1884. An additional concrete structure was added to the top of the bridge in 1930, when the roadway was widened. Overall, the bridge appears to be in fair condition, with some deterioration noted. The author has ranked this bridge as being highly significant, as it is a rare example of a helicoidal stone arch.
Citations
| Builder and build date | Seventh Street Improvement Arches (Bridge 90386) Bridge Report |
| Railroad History Citation | ICC Valuation Information, Compiled by Richard S. Steele |