It is entirely within Suffolk County and primarily serves the peninsular town of Winthrop from East Boston and Revere.

The route continues along Saratoga Street east until crossing into Winthrop over a bridge at Belle Isle Inlet.

This residential section of Winthrop features Donovan's Beach which offers a view of the Boston skyline looking west-southwest across Logan Airport.

[2] Pleasant Street continues south then bears left a few times before becoming Washington Avenue, where Route 145 travels east to meet Veterans Road.

Along Veterans Road the route heads north through Winthrop and then bears left at the intersection with the north end of Winthrop Shore Drive to become Crest Avenue and then Revere Street, heading generally northwest.