WIS 66 originally began at the corner of Reserve and Main streets in downtown
Stevens Point however once
US Highway 10 (US 10) finished the expansion of the bypass around Stevens Point deserting the old US 10, plans arose to expand WIS 66 to use the former highway. This is how WIS 66 got its current-day route, which begins in Wisconsin Rapids traveling east on the Old CTH-P, it then adjoins the former US 10 which routes through downtown Stevens Point, passing the
University of Wisconsin–Stevens Point campus, and later joins with current US 10,
US 51, and
Interstate 39 (I-39) traveling north. This creates a wrong-way concurrency with
WIS 66 and
US 10. WIS 66 then departs from I-39/US 10/US 51 and continues northwest past the
Stevens Point Municipal Airport, heading east at
Jordan near the Jordan County Park of
Portage County. This stretch and the remainder of the highway is the only part of the original WIS 66 before the 2009 highway expansion project. After crossing CTH-J near the unincorporated town of
Ellis, WIS 66 turns northwest again to
Rosholt, where it becomes Grand Avenue. WIS 66 ends at the western intersection with
WIS 49. Grand Avenue continues on as WIS 49 eastward. ==History==