Once you're in the Keys, U.S.1 becomes the Overseas Highway, which is our Main Street(the ONLY road). The best way to get around is to know the mile marker of your destination. Look for the little green mile-marker signs on the side of the highway. They begin just south of Florida City with number 127 and run all the way down to zero in Key West. Think of them like addresses. If you know the mile marker, getting there is easy. Here's a quick guide: My marina is at mm 91, so you can determine your distance from your hotel.