According to the United States Census Bureau, the town has a total area of 35.59 square miles (92.18 km2), of which 32.20 square miles (83.40 km2) is land and 3.39 square miles (8.78 km2) is water. Located beside Merrymeeting Bay at the mouth of the Androscoggin River, Topsham is drained by the Cathance River, Little River and Muddy River.
|Cities and towns (E)|
|Cities (✝ means a county seat)
Acton • Augusta✝ • Bangor • Bath✝ • Belfast✝ • Biddeford • Caribou • Ellsworth✝ • Lewiston-Auburn✝ • Portland • Presque Isle • Saco • Sanford