an island of the United States of North America, part of Monroe county, Florida, and one of the Pine group, forming the most southern territory of the United States, in N. Lat. 24.31°, and W. Long. 81.36°. It is 4 miles long by 1 in breadth at the widest part. Its position commands the trade of the Mexican Gulf, an advantage of which the government have availed themselves by constituting it a naval and military station. Like the rest of the Archipelago it is a coral formation, and has but a scanty soil. The climate, however, is so salubrious that Key West has become the resort of invalids from the Northern States. The inhabitants trade in wrecks, salt, sponges, and coral. Key West town has a safe and convenient harbour much resorted to. Pop. of town about 3000.