1855
An act gave the Milwaukee & Mississippi Company authority to continue their Milton & Janesville branch to the Mississippi River.
Nation and worldGrade A · 1 independent source
The evidence
“This branch was opened for traific in January, 1853. In 1855, an act of the Legislature was passed, giving the Milwaukee & Mississippi Company authority to continue their Milton & Janesville branch from the latter point through the villages of Monroe, ShuUsburg and Benton to the Mississippi River, opposite or near Dubuque. The Southern Wisconsin Company was then absorbed by the Milwaukee & Mississippi.”
1879-history-of-rock-county/10-rock-county-ch04-early-maps-courts-railroads.md, PDF p. 384 / book p. 388
Butterfield, C. W., et al. The History of Rock County, Wisconsin: its early settlement, growth, development, resources, etc. Chicago: Western Historical Company, 1879. Cornell University Library via the Internet Archive, archive.org/details/cu31924028871585.
Grade A: Found on a page of one of our sources