Due to its location in the western North Atlantic some 600 miles off the Carolinas and halfway between Halifax in Canada and Jamaica in the West Indies, the island of Bermuda was a key naval haven for the Royal Navy over the centuries. It was vital for the Navy first in the development of its American colonies, then during its rivalry with the United States, and finally as allies with the United States. The need to defend its 64 miles of coastline and ports has resulted in the construction of about 50 forts from 1617 to 1945 even though its total land mass is only 20.6 square miles.