US-1 lane closure in Key Largo cleared after overnight construction blockade

A planned construction closure on southbound US-1 at mile marker 92 in Key Largo held the left lane overnight and was cleared by early morning, cutting off a bottleneck on Monroe County’s main highway spine. Florida 511 pushed multiple traffic updates through the night as drivers moved through one of the Keys’ most sensitive choke points.

The lane restriction mattered because US-1 is the primary roadway providing access from Key Largo to Key West. In the Upper Keys, even a single-lane closure can slow traffic quickly, especially when commuters, service crews, delivery trucks and visitors all funnel onto the same road. That is why overnight work windows are used so often in the Florida Keys: they reduce daytime disruption, but they still can affect anyone leaving early for work, school or appointments.

Florida 511, which provides up-to-the-minute alerts on crashes, construction, closures, detours and travel times, is one of the main tools drivers rely on before heading out. FDOT and county transportation planners repeatedly emphasize that checking live conditions can make the difference between a routine drive and a long backup, especially when work is concentrated on the only highway corridor linking the island chain.

The overnight closure came against a backdrop of ongoing road and bridge work across Monroe County. FDOT’s Monroe County project listings show multiple active and planned U.S. 1 projects in the Keys, including bridge rehabilitation, roadway work, landscaping and resurfacing. Those projects are spread across the corridor, which means lane shifts and short-term closures can appear with little margin for error on a road that has no true alternate route.

Monroe County’s transportation planning materials also note that traffic volumes swing significantly by season, adding pressure during busy travel periods and making timing critical for crews. The county has seen how fast that pressure can build: in February 2025, a water transmission main replacement in the Upper Keys created heavy congestion between Key Largo and Islamorada and forced Monroe County sheriff’s deputies to direct traffic.

For drivers who depend on US-1 for work, school runs, supply deliveries and day-to-day travel, the Key Largo closure was a reminder of how fragile movement can be on the Keys’ single main artery. By early morning, the lane was open again, but the night’s congestion underscored how quickly overnight construction can spill into the first hours of the day.