It runs from US 44 in North Providence to Worrall Street in Downtown Woonsocket.

The route connects the cities of Providence and Woonsocket via the town center of Smithfield.

Route 104 begins as Waterman Avenue at an intersection with US 44 in North Providence.

The road name changes to Farnum Pike as the route passes through the Georgiaville section of the town.

State maintenance of the road ends at the intersection with Route 146A at the city line but signage for Route 104 continues into downtown Woonsocket, ending at Worrall Street.