Overseas Highway - Mile Markers

Locations along the Overseas Highway from Key West to Key Largo are commonly given as mile markers. The Florida Department of Transportation (FDOT) maintains mile marker signs every mile along the highway. Numbering starts in Key West, and increases towards the east and northeast up the path of the highway over the keys. Businesses along the highway began listing their locations by mile markers, adding decimal parts to more precisely indicate locations between mile marker signs. Outside of Key West and the City of Marathon, street addresses along the highway are based on the mile markers, using a four- to six-digit number (with no decimal point); the numbering pattern is as follows:

• The first three (or four) digits denote the approximate mile marker
• The last two digits denote a particular address; an even digit denotes an address on the Atlantic Ocean side while an odd digit denotes an address on the Florida Bay/Gulf of Mexico side

As an example, the Tropical Research Laboratory of Mote Marine Laboratory has a physical address of 24244 Overseas Highway. The first three digits indicate that it is near mile marker 24.2 (it is located on Summerland Key) while the last two digits indicate that it is located on the Atlantic Ocean side of the highway.