UP Davis Street Bridge (Arlington Heights)

In the early 1850s, several railroad companies began constructing railroad lines radiating from Chicago. The Illinois & Wisconsin Rail Road Company constructed 39 miles of new railroad, extending from Chicago to Cary, Illinois.  The following year, the railroad would be controlled by William B. Ogden, and consolidated into the Chicago, St. Paul & Fond du Lac Rail Road (CStP&FDL).  The CStP&FDL constructed an additional 53 miles to Janesville, Wisconsin in 1855.  The CStP&FDL would be purchased by the Chicago & North Western Railway (C&NW) in 1859.  The C&NW was beginning to construct and acquire a large network of railroads throughout the Midwest.  This line formed a portion of the principal northwest mainline of the C&NW, eventually extending to St. Paul, Minnesota.  At Janesville, traffic was required to run south to Afton to reach the line to Janesville.  Due to increasing traffic along this line, a second track would be constructed beginning in 1882, when a second track was completed from Chicago to Mayfair (Montrose Avenue).  By 1884, the route was double tracked to Des Plaines. 

In 1886, the Janesville & Evanston Railway was incorporated by the C&NW to construct 16 miles of new railroad, connecting Janesville with the existing line at Evansville, Wisconsin.  The railroad would be purchased by the C&NW the following year. By 1893, further double tracking was constructed to Barrington, followed by from Barrington to Janesville between 1898 and 1899.  In the late 19th Century, railroad traffic had become a significant safety hazard for the City of Chicago.  A solution was devised to elevate the railroad tracks throughout the city, placing the railroads upon embankments and constructing subways at each street.  In 1899, the C&NW completed a track elevation from Sangamon Street to Kostner Avenue; followed by Kostner Avenue to Foster Avenue in 1918.  During each of these elevation programs, a third track would be constructed. A third track was completed to Barrington in 1930.  The C&NW would become a prominent railroad in the Midwest, eventually building a system over 11,000 miles long.  Throughout the 20th Century, this line would continue to be an integral part of the C&NW system.  The second track would be removed between Janesville and Harvard in the 1950s.  In 1995, the C&NW would be purchased by the Union Pacific Railroad.  Union Pacific continues to operate the route as the Harvard Subdivision.  Metra operates a commuter service, the Union Pacific-Northwest Line over the Chicago to Harvard section.