Construction of the Milwaukee & Northern (M&N) commenced in the summer of 1870 at Schwartzburg Junction, Wis., where the M&N connected with the Chicago, Milwaukee & St. Paul (CM&StP), also known as the Milwaukee Road (MILW).
By the end of 1870, the M&N had completed 13.7 miles of main line to Cedarburg. The official opening of the line to Cedarburg was celebrated on 27 January 1871.
In 1871, 79 miles of track were laid from Cedarburg to Hilbert Junction, and from there to Menasha.
The majority of this portion of the main line is still active, some of it is operated by the Canadian National (CN), some of it is operated by the Wisconsin & Southern (WSOR).