- 1857: 44 miles completed from Clinton to Wheatland, Iowa by the Chicago, Iowa and Nebraska Railroad
- 1858: 20 miles completed from Wheatland to Lisbon, Iowa by the Chicago, Iowa and Nebraska Railroad
- 1859: 17 miles completed from Lisbon to Cedar Rapids, Iowa by the Chicago, Iowa and Nebraska Railroad
- 1861: 41 miles completed from Cedar Rapids to Belle Plaine, Iowa by the Cedar Rapids and Missouri River Railroad
- 1861: 41 miles completed from Cedar Rapids to Chelsea, Iowa by the Cedar Rapids and Missouri River Railroad
- 1862: 29 miles completed from Chelsea to Marshalltown, Iowa by the Cedar Rapids and Missouri River Railroad
- 1864: 29 miles completed from Marshalltown to Nevada, Iowa by the Cedar Rapids and Missouri River Railroad
- 1865: 29 miles completed from Nevada to Boone, Iowa by the Cedar Rapids and Missouri River Railroad
- 1867: 150 miles completed from Boone to Council Bluffs, Iowa by the Cedar Rapids and Missouri River Railroad
- 1867: 6 miles completed from Missouri Valley to California Junction, Iowa by the Cedar Rapids and Missouri River Railroad
- 1884: CI&N and CR&MR officially acquired by Chicago & North Western Railway
- 1887: 6 miles completed from Beverly to Otis, Iowa bypassing Cedar Rapids by the Linn County Railway
- 1887: Linn County Railway acquired by Chicago & North Western Railway
- 1891-98: Second track constructed between Clinton and Cedar River
- 1898-1900: Second track constructed between Cedar River and Mashalltown
- 1898-1901: New alignment completed between Boone and Ogden, Iowa; including the Des Moines River Bridge
- 1900-02: Second track constructed between Marshalltown and Council Bluffs
- 1933: Old route via Moingona between Boone and Ogden abandoned
- 1995: Chicago & North Western purchased by Union Pacific Railroad
- 1995-Present: Union Pacific operates the Clinton Subdivision between Clinton and Boone
- 1995-Present: Union Pacific operates the Boone Subdivision between Boone and Missouri Valley
- 1995-Present: Union Pacific operates the Omaha Subdivision between Missouri Valley and Council Bluffs
11/07/21
This interesting bridge crosses the East Boyer River in Denison.
Built in 1902, the bridge features a standardized design. The main span of the bridge is a large Quadrangular Through Truss, while the approach is a simple through girder span. The entire bridge is set onto concrete substructures.
What is uncommon is the layout of the three tracks. The bridge appears to have been built by simply combining a single and double track structure. According to railroad sources, the single track span was added in 1910.
This creates a unique look, where the double track span uses M Frame portal bracing, and the single track uses an A Frame. The third track once carried a C&NW branch heading north to Wall Lake, which was abandoned 1942.
Overall, the bridge appears to be in fair condition. Years of flooding have resulted in the pier being reinforced with sheet metal on the bottom.
Historic photo of the bridge
The author has ranked this bridge as being regionally significant, due to the exceptionally unique triple tracked truss. This may be the only triple track truss ever built for the C&NW.
Unfortunately, the bridge will be replaced in late 2021. Union Pacific had offered the single track span for free, assuming one can move it. As of November 7th, 2020; replacement work had begun by building a new track to use the single track span while the double track portion is replaced.
The photo above is an overview. The bridge can be accessed from 8th Avenue.