The County of Cumberland was incorporated in 1760, named after William, Duke of Cumberland, son of King George II.
The county is comprised of three cities: Portland, South Portland, and Westbrook and twenty-five towns: Baldwin, Bridgton, Brunswick, Cape Elizabeth, Casco, Chebeague Island, Cumberland, Falmouth, Freeport, Frye Island, Gorham, Gray, Harpswell, Harrison, Long Island, Naples, New Gloucester, North Yarmouth, Pownal, Raymond, Scarborough, Sebago, Standish, Windham, and Yarmouth. The city of Portland is the county seat.
The area of the County is 853 square miles. The population as of December 2010 is 281,674.