State Route 24 (abbreviated SR 24) is part of Maine's system of numbered state highways, running from Bailey Island south of Orr's Island in Harpswell northward to Gardiner, passing through Brunswick along the way.

SR 24 begins at an intersection with Abner Point Road on Bailey Island in the town of Harpswell.

It proceeds northward through the "downtown" area of Harpswell on Orr's Island and continues onto mainland Maine where it crosses into the town of Brunswick.

From Topsham, SR 24 was designated over a new routing to its current northern terminus in Gardiner and ultimately as far as Guilford.

This re-routing reduced the overall length of SR 24 by approximately one mile (1.6 km) and eliminated its concurrency with US 201.