Mill Street Overpass (Lodi)

In 1860, the Beloit and Madison Railroad (B&M) constructed 17 miles of railroad, extending from Beloit, Wisconsin to Magnolia, Wisconsin.  In 1864, the B&M constructed an additional 32 miles of railroad, extending from Magnolia to Madison, Wisconsin.  In 1864, the Madison, Lodi and Baraboo Railroad (ML&B) began grading for a new railroad line, extending from Baraboo, Wisconsin to Merrimac, Wisconsin.  The ML&B was acquired by the Baraboo Air Line Railroad (BAL) in 1870, and began construction on a line extending from Reedsburg, Wisconsin to Madison.  In 1870, the La Crosse, Trempealeau and Prescott Railroad (LCT&P) constructed an additional 29 miles of railroad, extending from the Winona & St. Peter Railroad (W&StP) at Winona, Minnesota to the north side of La Crosse, Wisconsin; constructing a large bridge across the Mississippi River.  The BA&L and the B&M were acquired by the Chicago & North Western Railway (C&NW) in 1871.  The C&NW continued construction, eventually opening a 129 mile line between Madison and present-day Medary on the north side of La Crosse in 1873.  This line was difficult to construct, as it crossed through areas of rugged terrain, requiring three tunnels and numerous wooden trestles.  The LCT&P was purchased by the C&NW in 1876.

Soon after completion, this line became an important route for the C&NW.  The line connected an existing mainline to Chicago with the existing W&StP mainline across southern Minnesota.  In addition, the Chicago, St. Paul, Minneapolis & Omaha Railway (Omaha Road, a C&NW subsidiary) mainline ended at this line in Elroy, Wisconsin, providing the C&NW with a connection to the Twin Cities.  Numerous improvements were made in the late 1870s and throughout the 1880s, including filling wooden trestles and replacing wooden bridges with iron and stone.  The C&NW constructed a short 4-mile branch line from Medary to La Crosse in 1886.  By the late 19th Century, traffic over this route had grown to the point that a second track was necessary.  Between 1896 and 1899, the C&NW completed a second track between Evansville, Wisconsin and Elroy.  By the early 20th Century, the C&NW was operating an expansive railroad network throughout the Midwest, radiating north and west from Chicago.  This line initially served as one of the principal mainlines of the railroad, connecting Chicago to the Twin Cities and the mainline to South Dakota.

Between 1910 and 1912, the C&NW undertook a large construction program to construct shorter routes and streamline operations.  A cutoff between Milwaukee and Sparta opened in 1911, reducing the importance of this line.  Between 1953 and 1956, much of the double track would be removed.  A portion of the line was abandoned between Elroy and Sparta in 1964, and became one of the United States first rail-trail projects.  In 1978, the Sparta to Medary and Winona to Trempeleau, Wisconsin segments would be abandoned, followed by the Beloit to Evansville segment in 1979 and the Medary to Trempeleau and La Crosse segments in 1981.  The Reedsburg to Elroy segment was abandoned in 1987.  All of the line west of Reedsburg would be acquired by the Wisconsin Department of Natural Resources for trail use.  

In 1995, the C&NW would be purchased by Union Pacific Railroad (UP).  In 1996, UP leased the Fitchburg to Reedsburg segment to the Wisconsin & Southern Railroad (WSOR).  In addition, UP attempted to abandon the Evansville to Fitchburg segment the same year.  In response to possibly losing railroad service, the communities of Fitchburg and Oregon purchased the line, although it was out of service.  In 2014, the State of Wisconsin acquired the Fitchburg to Reedsburg line, and contionued to lease it to WSOR.  The same year, WSOR began operations over the Oregon to Fitchburg line, while the Evansville to Oregon segment remains out of service.  Today, WSOR operates the Reedsburg Subdivision between Madison and Reedsburg.  The 400 State Trail uses the former railroad between Reedsburg and Elroy; the Elroy-Sparta State Trail uses the former railroad between Elroy and Sparta; the La Crosse River State Trail uses the former railroad between Sparta and La Crosse; and the Great River State Trail uses the former line between Medary and Marshland.