This is the Turnpike Extension that meets US 1 in Florida City, which takes you to Key Largo, some 22 minutes south. From the west, come across I-75 (Alligator Alley) to the Miami exit and south to the Turnpike Extension. From Miami International Airport, take LeJeune Road south to 836 West, going to Turnpike Extension, south to US 1 and to the Keys.
Driving in the Keys requires use of Mile Markers. The Overseas Highway is like Mainstreet. The best way to get around is to know the mile marker of your destination. These little green signs that dot the highway every mile begin just south of Florida City with number 127 and run all the way down to zero in Key West. They're like the addresses of everything found in The Keys. If you know the mile marker then getting where your going is a cinch!