About Monroe County Monroe County is the southernmost county in Florida and the United States. It is made up of the Florida Keys and portions of the mostly uninhabited Everglades National Park and Big Cypress National Preserve. The Florida Keys string of islands are connected by U.S. 1, which ends in Key West, 150 miles southwest of Miami. Just miles offshore on the Atlantic side of the Florida Keys is the only living coral reef in the continental United States. The county seat is in the City of Key West. Other incorporated areas include Marathon, Islamorada, Key Colony Beach and Layton. Monroe County has government offices in Key West, Marathon, and Key Largo. http://www.monroecounty-fl.gov http://www.fla-keys.com