The Illinois General Assembly chartered the Aurora Branch Railroad on February 12, 1849 to build a branch of the Galena and Chicago Union Railroad to Aurora, which it opened on September 2, 1850. The company was renamed Chicago and Aurora Railroad on June 22, 1852, and given expanded powers to extend from Aurora to a point north of LaSalle; this extension, to Mendota, was completed on October 20, 1853. Another amendment, passed February 28, 1854, authorized the company to build east from Aurora to Chicago via Naperville, and changed its name to Chicago and Southwestern Railroad. The latter provision was never acted upon, and was repealed by an act of February 14, 1855, which instead changed the name to Chicago, Burlington and Quincy Railroad (CB&Q). The Aurora-Chicago line was opened on May 20, 1864, by which time the CB&Q had, through acquisitions, acquired a main line from Chicago to Galesburg, where it split into branches for Burlington and Quincy.
The portion of the Chicago and Aurora between Aurora and Mendota remains a main line of CB&Q successor BNSF Railway, which calls it the Mendota Subdivision. The original West Chicago-Aurora branch line is now an industrial track of the Chicago Subdivision.