- 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
06/26/21
This standard 1940s I-Beam bridge crosses over 500th Avenue/Y Avenue just west of Ames.
The bridge is set onto concrete substructures and contains 2 sets of I-Beams, with 4 beams in each set.
Built in 1941, the bridge replaced an earlier through girder bridge, which can be seen here. Photo is courtesy of the Iowa Department of Transportation.
It is unknown why this bridge was replaced, although it could have possibly had to do with the paving of the road. It is unknown if the original span was moved to another location.
The author has ranked this bridge as being minimally significant, due to the common design and newer age.
The photo above is an overview. The bridge can be accessed from the road below.