After briefly running through the city of Merrill's Sixth Ward along West Main Street, the two highways cross over the Wisconsin River—twice.

The river is divided by a small island where West Main Street crosses into the uptown portion of the city of Merrill.

The two highways separate at the Y-intersection of Grand Avenue and Main Street; WIS 64 continues east over the Prairie River into downtown Merrill, while WIS 107 turns sharply to the northwest along Grand Avenue.

WIS 107 continues northwest, past the Merrill Area Recreation Complex and the main entrance to Council Grounds State Park, before turning north out of the city.

When the US 51 bypass freeway was finished east of the city, the former route of US 51 was turned back to county control, resulting in the unusual terminus.