CPKC Bridge #Z-234

In 1872, the Chicago and Pacific Railroad was charted to construct a new 88-mile railroad line extending from Chicago, Illinois to Byron, Illinois.  Construction began on the line in 1873, and the line was completed to Elgin in 1874, followed by to Byron in 1876.  In Chicago, the railroad crossed the Chicago River three times, crossed Goose Island and turned west along Bloomingdale Avenue.  In 1880, the railroad came under lease of the Chicago, Milwaukee & St. Paul Railway, commonly known as the Milwaukee Road.  The Milwaukee Road continued construction, reaching Kittredge, Illinois in 1882.  At Kittredge, this line connected to a line that had been completed to Savanna, Illinois by the Northern Illinois Railroad in 1862.  This line became a principal mainline for the Milwaukee Road, later extending across Iowa to reach Omaha.  Because of the importance of this line, the portion of the line west of Bloomingdale Avenue in Chicago to Bensenville was double tracked in 1885.  In 1892, construction on a second track began between Bensenville and Genoa, which would be completed in 1897.  By 1899, the line was double tracked to Savanna. 

By the 20th Century, the Milwaukee Road had become a prominent railroad in the United States, operating a network of railroad lines primarily in the Midwest.  The Milwaukee Road was often in financial trouble, especially after the costly Pacific Extension was completed in 1909. In 1925, the company declared bankruptcy, and reorganized as the Chicago, Milwaukee, St. Paul and Pacific Railroad in 1928.  This line continued to serve as a critical mainline for the railroad during the 20th Century, as it provided a connection between Chicago and the mainlines to Omaha and Kansas City.  Significant upgrades were made during the 1930s and 1940s, including replacing bridges and revising curves.  During the 1970s, conditions of the line gradually deteriorated, and much of the second track was removed in the late 1970s. 

Portions of the line in Chicago were removed in the late 1970s.  By 1985, a suitor for the Milwaukee Road was being sought, and the Soo Line Railroad, controlled by Canadian Pacific Railway (CP) purchased the Milwaukee Road in 1986.  In 1997, CP would sell the line segment to I&M Rail Link, which was purchased by the Dakota, Minnesota & Eastern Railroad (DM&E) subsidiary Iowa, Chicago & Eastern Railroad (IC&E).  Portions of the Bloomingdale Line between Pacific Junction and the Kennedy Expressway were abandoned in 2001.  Chicago Transfer Railway (CTR) began operations around Goose Island in 2007, using former Milwaukee Road trackage.  The DM&E/IC&E were purchased by Canadian Pacific in 2008.  The CTR trackage was abandoned in 2018.  CP merged with Kansas City Southern Railway in 2023 to form CPKC.  Today, CPKC operates the Elgin Subdivision between Pacific Junction and Randall Road in Elgin; and the Chicago Subdivision between Elgin and Savanna.  In addition, Metra operates commuter service as the Milwaukee West line over the Elgin Subdivision.