IAIS Old US-6 Bridge (Menlo)

In 1869, the Chicago, Rock Island & Pacific Railroad (Rock Island) constructed 142 miles of new railroad, extending from the end of the existing mainline at Des Moines, Iowa to Council Bluffs, Iowa.  Originally, the line went west to Atlantic, Iowa; before turning northwest and going through Avoca, Iowa and Shelby, Iowa.  At Shelby, the line would turn back southwest, and run through Neola, Iowa and Underwood, Iowa before arriving in Council Bluffs.  In 1880, the Rock Island was reorganized as the Chicago, Rock Island & Pacific Railway.  The Rock Island constructed and acquired a large network of railroads during the late 19th Century, covering much of the central United States.  This line became part of the principal mainline of the Rock Island, and allowed for further development of branch lines throughout central Iowa and eventual expansion west of the Missouri River.  In the late 19th Century, several improvements were made to the line, including revising grades, curves and replacing wooden bridges with stone and iron structures. 

The Rock Island struggled financially throughout much of its history, experiencing repeated bankruptcies and chronic instability.  After World War II, the Rock Island struggled to survive, proposing mergers and deferring maintenance on their routes. The railroad reorganized as the Chicago, Rock Island & Pacific Railroad in 1948. During the early 1950s, the Rock Island undertook a series of improvements in Western Iowa to eliminate harsh grades and shorten the line.  Between 1952 and 1953, the Rock Island constructed the Atlantic Cutoff, which included constructing 34 miles of new railroad between Atlantic and McClelland, Iowa.  West of McClelland, the Rock Island used the Chicago Great Western Railway (CGW) tracks to reach Council Bluffs. The new route saved 10 miles, and much of the old route was abandoned in 1953.  A short segment was retained between Walnut, Iowa and Shelby, which was abandoned in 1966.  An additional revision was made near Adair in 1954, which involved straightening the route.  By the mid-1970s, the railroad was in serious decline.  The railroad secured loans to eliminate slow orders, acquired new equipment, and attempted to restore profitability.  Several sections of this line had fallen into serious disrepair, hampering the Rock Islands ability to maintain efficient operations.  In 1978, the railroad came close to profit, but creditors were lobbying for a complete shutdown of the Rock Island.  During the fall of 1979, a strike crippled the railroad, and by January of 1980, the entire system was ordered to be shut down and liquidated.  Many of the lines and equipment were scrapped.  Profitable sections of railroad were prepared for sale.  

In November 1981, the Iowa Railroad Company (IARR) began operations over the former Rock Island mainline in western Iowa.  In June 1982, the IARR entered into a two-year lease for the entire Rock Island mainline between Bureau, Illinois and Council Bluffs.  In 1983, concerns had grown over the ability of the IARR to provide reliable service to shippers along the line, and several industries came together to form Heartland Rail Corporation, which purchased the line between Bureau and Council Bluffs from the Rock Island trustees.  Iowa Interstate Railroad (IAIS) was chosen to operate the line, and began operations in late 1984.  After years of thin profit margins, IAIS began making significant financial strides in the 1990s and early 2000s, eventually becoming a major railroad in central Iowa.  Increased profit margins and large grants meant IAIS could rebuild deteriorated track, improve bridges and expand operations.  Today, IAIS continues to operate the Council Bluffs Subdivision between Des Moines and Council Bluffs.  Except for a short portion near Shelby, the entirety of the original mainline between Atlantic and Council Bluffs remains abandoned.