State Route 137 (SR 137) is a route that runs west to east that begins at the intersection of US 2 in East Mercer and covers a large expanse of land, ending in the city of Belfast at SR 3.
SR 137 is the main road in the communities of Smithfield and Oakland, on the western terminus of the route. SR 137 changes abruptly to Business 137 as it goes through a business district in the city of Waterville, the main hub of Northern Kennebec county.[clarification needed]
After returning to SR 137, it meets US 202 in the town of China, where they become one road until an intersection in the town of Albion splits them. At this intersection, SR 137 becomes known as Belfast Road. Next, SR 137 crosses through the towns of Freedom and Knox, meeting SR 220 at "Knox Corner". In Morrill, SR 137 crosses SR 131 at an intersection. Eventually, at the end of the route, SR 137 merges with SR 7, and both end at SR 3, one of the main roads of Belfast.
State Route 137 Business (SR 137 Bus.) is a business route through the towns of Waterville and Winslow. Route 137 goes through the city, but it does not go into the downtown area like Route 137 business. The entire route is in Kennebec County.