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| Name | UP Sibley Parkway Bridge Chicago & North Western Railway Bridge #421 |
| Built By | Chicago, St. Paul, Minneapolis & Omaha Railway (South Track) Chicago & North Western Railway (North Track) |
| Currently Owned By | Union Pacific Railroad/Canadian Pacific Kansas City Limited |
| Superstructure Contractor | Unknown |
| Length | 227 Feet Total, 36 Foot Main Span |
| Width | 2 Tracks |
| Height Above Ground | 13 Feet 0 Inches |
| Superstructure Design | Deck Plate Girder and Timber Pile Trestle (South Track) Steel Stringer and Timber Pile Trestle (North Track) |
| Substructure Design | Timber Pile and Steel Pile |
| Date Built | 1896 (South Track) c. 1930 (North Track) |
| Traffic Count | 15 Trains/Day (Estimated) |
| Current Status | In Use |
| Chicago & North Western Railway Bridge Number | 421 (South Track) M-1603 (North Track) |
| Union Pacific Railroad Bridge Number | 86.84 |
| Significance | Local Significance |
| Documentation Date | 8/27/2011 |
In 1865, the Minnesota Valley Railway Company (MVR) began construction on a new railroad line between Mendota, Minnesota and St. James, Minnesota. In 1865, the first 22 miles were completed between Mendota, Minnesota and Merriam Junction, Minnesota; followed by 17 additional miles to Belle Plaine, Minnesota in 1866. In 1867, the MVR completed an additional 16 miles to Le Sueur, Minnesota; followed by 12 additional miles to Kasota, Minnesota in 1868. In 1869, the MVR completed an additional 22 miles to Lake Crystal, Minnesota. The same year, an additional 5 miles would be completed between St. Paul, Minnesota and Mendota. In 1870, the MVR would be purchased by the St. Paul and Sioux City Railroad (StP&SC). 22 additional miles to St. James, Minnesota would be completed in 1870. The StP&SC completed 58 more miles from St. James to Worthington, Minnesota in 1871; and 64 additional miles to Le Mars, Iowa were completed in 1872. At Le Mars, the route connected to an existing railroad, over which the StP&SC used trackage rights to reach Sioux City, Iowa.
In 1881, the StP&SC would be sold to the Chicago, St. Paul, Minneapolis & Omaha Railway (Omaha Road). The Omaha Road would come under control of the Chicago & North Western Railway (C&NW) the next year. The C&NW had developed a large network of railroad lines in the Midwest, with the Omaha Road serving as the northern extent of the company. This route became the main line of the Western District of the Omaha Road. Several improvements were made to the line in the late 19th and early 20th Centuries. Between 1898 and 1906, several sections of the line were realigned between Blakeley, Minnesota and Mankato. In 1957, the C&NW leased the Omaha Road, and the C&NW purchased the company in 1972. The C&NW was purchased by Union Pacific Railroad (UP) in 1995. UP still operates the St. Paul to St. James segment as the Mankato Subdivision and the St. James to Sioux City segment as the Worthington Subdivision. The line remains a mainline for UP, connecting St. Paul to Sioux City and providing UP with a mainline into the Twin Cities.
Located near US Highway 169 in Mankato, this deck girder and steel stringer bridge carries the former Chicago & North Western Railway/Chicago, St. Paul, Minneapolis & Omaha Railway over Sibley Parkway. Little is known about the history of this bridge. In 1896, the Omaha Road realigned their line through Mankato, and constructed a deck girder and timber pile trestle bridge at this location. The C&NW added a similar span to the north side of the bridge at that time. It appears that the bridge was modified in approximately 1930, by replacing the main span of the north track with a steel stringer, and strengthening the main span of the south track with additional girder lines, giving the bridge its current configuration.
Currently, the south track of the bridge consists of a 36-foot deck plate girder span, approached by timber pile trestle spans and supported by timber pile substructures. The north track of the bridge consists of a 36-foot steel stringer span, with the same approaches and substructures. Two different contractors fabricated the steel spans for the superstructure. The south track girder span uses six girder lines, and appears to have been strengthened long ago. Railroads often reused steel spans, as it was an inexpensive way to repair other steel spans which had become too light for traffic. No information is known about the additional girders, although it is likely that they were fabricated in c. 1895 and originally used at an unknown location. Since the last reconstruction, the bridge has seen few changes. The east pier of the south track was replaced by a steel bent in the 2020s. Bridges such as this were commonly used by railroads, as they were easy to construct and economical. Overall, the bridge appears to be in fair to poor condition, with significant deterioration throughout the timber components of the bridge. It is likely that this bridge will be replaced in the coming years. The author has ranked the bridge as being locally significant, due to the common design and unknown history.
Citations
| Build date | National Bridge Inventory (NBI) |
| Railroad History Citation | ICC Valuation Information, Compiled by Richard S. Steele |