It runs through Largo, where it crosses an interchange with US 19 and east of the intersection, SR 686 is known as Roosevelt Boulevard, named for President Franklin Delano Roosevelt.

It then travels in a southeastern direction through Clearwater, and intersects SR 688 (Ulmerton Road), and heads east with a concurrency for just under a mile.

At the end of the concurrency, SR 686 once again heads southeast, entering St. Petersburg.

The route currently runs from the foot of the 118th Avenue Connector westbound offramp (milepost 1.582) to just east of the I-275 on-ramps (milepost 3.021).County Road 416 extends from Gulf Boulevard in Belleair Beach, east to Clearwater-Largo Road in Largo.

West Bay Drive is historically Largo's "Main Street".