The original 1918 routing of WIS 23 ended the route on the western terminus at Packwaukee at its junction with WIS 10. The route to the east of that point still exists as it is today. The route was extended in the early 1920s to the southwest, following its present routing from Packwaukee through Kilbourn (present day Wisconsin Dells), Reedsburg and Dodgeville, then along present day US 151 from Dodgeville to Dubuque, Iowa via Mineral Point and Platteville. Later in that decade, the route was truncated back to Dodgeville when US 118 was signed, but then extended again – this time along its current route when US 118 became part of US 151.