Lower Keys · Marathon to Key West

The Lower Keys on US-1, one way: from Marathon the route crosses the Seven Mile Bridge, passes Bahia Honda State Park and Big Pine Key and ends at the Southernmost Point in Key West, at Mile Marker 0. It's 49 miles of water on both sides and no toll. FDOT is rehabilitating the Seven Mile Bridge until summer 2029, with single-lane closures on weeknights, so ride it by day. The bridge gets strong crosswinds, Key deer cross on Big Pine Key, and with one road in and out, a crash or a storm closes it all.

The Overseas Highway follows the line of Henry Flagler's railroad, which ran to Key West from 1912 until the Labor Day Hurricane of 1935 wrecked it; the state bought the right of way and the road opened in 1938 on the old railroad bridges. From Marathon the route crosses the Seven Mile Bridge, with the old bridge alongside; at Knight's Key, at the Marathon end, there's a parking lot for the old bridge and the trail to Pigeon Key. FDOT started rehabilitating the Seven Mile Bridge on March 2, 2026, with work planned until summer 2029 and single-lane closures at night on weeknights, so ride it by day.

Past the bridge the route reaches Bahia Honda State Park, with the old railroad bridge over the channel, and Big Pine Key, where the small Key deer cross the road and the zone is patrolled. The route ends at the Southernmost Point buoy in Key West, at Mile Marker 0. It's a one-way ride of 49 miles with no toll, strong crosswinds on the Seven Mile Bridge, and little fuel after Big Pine. It's one road in and out: a crash or a storm closes it all, and hurricane season runs from June 1 to November 30.