| State: | WI |
| Type: | WI |
| Route: | 91 |
| Map Custom: | yes |
| Map Notes: | WIS 91 highlighted in red |
| Length Mi: | 18.83 |
| Length Ref: | [1] |
| Length Round: | 2 |
| Direction A: | West |
| Direction B: | East |
| Terminus A: | in Berlin |
| Terminus B: | in Oshkosh |
| Counties: | Green Lake, Winnebago |
| Previous Type: | WI |
| Previous Route: | 90 |
| Next Type: | WI |
| Next Route: | 92 |
State Trunk Highway 91 (often called Highway 91, STH-91 or WIS 91) is a state highway in the U.S. state of Wisconsin. It runs east - west in east-central Wisconsin from near Berlin to Oshkosh.
Starting in WIS 49 in Berlin, WIS 91 starts to travel eastward, passing Koro. South of Waukau, it intersects WIS 116 and CTH-M. Going further east through the Oshkosh city limit, WIS 91 intersects and starts to run concurrently with WIS 44. However, as soon as they meet I-41/US 41 at a diamond interchange, WIS 91 ends there. WIS 44, on the other hand, continues northeast to downtown Oshkosh.
Initially, in 1919, WIS 91 was established along part of present-day WIS 44. It traveled from WIS 23/WIS 49 (now just WIS 23) in Ripon to WIS 15 (now US 45) in Oshkosh.[2] [3] In 1924, WIS 91 was relocated from the Ripon–Oshkosh route to the Merill–McCord route, causing CTH-E to move just northwest of its former route. This was done in response to the northeastern extension of WIS 44. The new route traveled from US 51 in Merill to US 8 in McCord along present-day WIS 107, pre-bypass alignment of WIS 10 (after 1926, US 51[4]), and present-day CTH-CC. It also functioned as an alternate route of WIS 10.[5] [6]
By 1935, WIS 91 was removed south of the intersection of US 51 (now CTH-A) north of downtown Tomahawk.[7] [8] In 1937, the rest of WIS 91 was removed in favor of turning this back to local control (replaced by CTH-CC).[9] [10] This time, the route remained decommissioned for around a year. By 1939, WIS 91 was readded right near the location of its second alignment. It traveled from US 51 (now CTH-A) north of Tomahawk to US 8 in Bradley.[11] [12] In the mid-1980s, WIS 91 was decommissioned again in favor of the opening of US 51's Tomahawk Bypass and CTH-U.[13] [14] It remained decommissioned until 1996 when WIS 91 was readded again, traveling from Berlin to Oshkosh. It superseded a southernmost portion of WIS 116 and CTH-X. This time, the new routing still exists to this day.[15] [16]