- 1867: 16 miles completed from Ackley to Eldora, Iowa by the Eldora Railroad and Coal Company
- 1868: 27 miles completed from Eldora to Marshalltown, Iowa by the Iowa River Railway
- 1868: Eldora Railroad and Coal Company sold to the Iowa River Railway
- 1869: Iowa River Railway sold to the Central Railroad Company of Iowa
- 1871: 65 miles completed from Northwood to Ackley, Iowa by the Central Railroad Company of Iowa
- 1871: 81 miles completed from Marshalltown to Albia, Iowa by the Central Railroad Company of Iowa
- 1878: Central Railroad Company of Iowa sold to Central Iowa Railway
- 1882: 98 miles completed from Oskaloosa to the Mississippi River across from Keithsburg, Illinois by the Chicago, Burlington & Pacific Railroad
- 1882: CB&P sold to the Central Iowa Railway
- 1883: 83 miles completed from Keithsburg to Peoria, Illinois by the Central Iowa Railway Company
- 1886: Mississippi River Bridge completed at Keithsburg by the Keithsburg Bridge Company
- 1889: Central Iowa Railway sold to the Iowa Central Railway
- 1895: Minneapolis & St. Louis Railway reorganizes as the Minneapolis & St. Louis Railroad
- 1901: Iowa Central Railway controlled by the Minneapolis & St. Louis Railroad
- 1901: Keithsburg Bridge Company sold to the Iowa Central Railway
- 1912: Iowa Central Railway sold to the Minneapolis & St. Louis Railroad
- Ca. 1920: Minneapolis & St. Louis Railroad reorganizes as the Minneapolis & St. Louis Railway
- 1960: Minneapolis & St. Louis purchased by the Chicago & North Western Railway
- 1962: Beacon, Iowa to Eddyville, Iowa segment abandoned, operations begin over parallel Rock Island tracks
- 1971: Oskaloosa, Iowa to Keithsburg, Illinois segment abandoned
- 1976: Keithsburg, Illinois to Middle Grove, Illinois segment abandoned
- 1988: Hampton, Iowa to Ackley, Iowa segment abandoned
- 1990: Rockwell, Iowa to Sheffield, Iowa segment abandoned
- 1995: C&NW purchased by Union Pacific Railroad
- 2001: Eddyville, Iowa to Albia, Iowa segment abandoned
- 2001: Sheffield, Iowa to Hampton, Iowa segment abandoned
- 2006: Ackley, Iowa to Marshalltown, Iowa segment sold to the Iowa River Railroad
- 2008: Middle Grove, Illinois to Peoria, Illinois segment abandoned
- 2011: Steamboat Rock, Iowa to Marshalltown, Iowa abandoned and purchased by Marshall and Hardin Counties
- 1995-Present: Union Pacific operates the Oskaloosa Subdivision between Marshalltown and Eddyville
- 2006-Present: Iowa River Railroad operates between Ackley and Steamboat Rock
- 2011-Present: Iowa River Rail Trail being developed between Steamboat Rock and Marshalltown
06/26/21
Utilizing a common design, this bridge crosses over 465th Avenue north of Searsboro.
Built in 1940, the standard span features an I-Beam approached by trestle spans. These rest on steel pile substructures.
It is likely that the piers were updated with the current steel pile piers in the 1990s.
The author has ranked the bridge as being minimally significant, due to the common design and newer age of the bridge.
The photo above is an overview. The bridge can be accessed from the road below.