The route still had gravel sections in 1953.

Most of the roads between these areas are dirt tracks, with a few improved gravel sections.

This change also bypassed the last remaining gravel section of the highway.

The last gravel sections on the road were paved in 1952.

In 1962, work began on paving the gravel sections of the highway.

Paving continued sporadically for the next 15 years, with the last gravel section on the route being paved in 1947.

The gravel section was upgraded to a more modern surface in 1950.

The only gravel section remaining by 1940 was south of Rushford.

This leads to a gravel section and a ford to access the east side of the creek.

By 1940, only two short gravel sections of Highway 15 remained, both paved by 1953.