Route 104 is a numbered State Highway running 14.9 miles (24.0 km) in Rhode Island. 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. It proceeds northwest into the town of Smithfield. The road name chanes to Farnum Pike as the route passes through the Georgiaville section of the town. The route soon crosses under I-295 without an interchange. Route 104 continues its northwest path through Smithfield center and eventually enters the town of North Smithfield. In North Smithfield, it turns north and intersects Route 7. Beyond the Route 7 junction, Route 104 shifts to Greenville Road, which bends eastward at Primrose Pond. Route 104 then reaches the city of Woonsocket, going along Providence Street and Main Street. 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.

The Rhode Island Department of Transportation Pavement Log shows Route 104 ending at the corner of Providence Street and South Main Street in Woonsocket. Signage, however, clearly shows Route 104 ending at Worrall Street. Some of this signage was put up by the City, some was put up by the State. Some old signage shows Route 104 continuing along Clinton Street (northbound) and Worrall Street and Social Street (southbound) to end at Route 126, but most of the southbound signs now say TO 104.

In 1808, a private toll road was built between North Providence and Smithfield known as the Farnum and Providence Turnpike along what is now the Farnum Pike portion of modern Route 104. In 1873 the State of Rhode Island purchased the road for $500 from the private owners and made the road free. Route 104 was designated in 1923 along the Farnum turnpike alignment with extensions on both ends into downtown Providence and downtown Woonsocket. In Woonsocket, the route originally ended at Route 126 (Cumberland Street). In Providence, the old route used Woonasquatucket Avenue and Manton Avenue to end at Route 128.