SR 77 begins in Scarborough at SR 207 near Scarborough Beach State Park. It runs east and north along the coastline, through the town of Cape Elizabeth. SR 77 passes through eastern South Portland before crossing the Fore River on the Casco Bay Bridge into downtown Portland.
Upon entering Portland proper, SR 77 crosses over U.S. Route 1A (US 1A) with indirect access available via connecting streets. The highway splits into a one-way pair, High Street northbound and State Street southbound. The SR 77 designation continues north for another 0.9 miles (1.4 km) before terminating at Park Street. This intersection is the signed eastern terminus of SR 22, and administratively SR 25, although the latter is not signed.[2] In addition, the highway also passes Cumberland Avenue just to the south, the former southern terminus of SR 26. The one-way northbound alignment of SR 77 on High Street is not officially part of the route as designated, because State Street was formerly a two-way street prior to 1972.[3]
SR 207 in Scarborough
US 1A in Portland
SR 22 / SR 25 in Portland
