Driving an RV down the Overseas Highway
Reviewed by Ben Kiser, RV rental operator and fleet consultant.
Key Largo to Key West is 113 miles and 42 bridges, with the Seven Mile Bridge in the middle. In an RV it is the best part of the trip. Three things decide how it goes: when you leave the mainland, which road you take onto the Keys, and where the RV sleeps.
- From the Princeton rental lots: Key Largo 35 road miles, Key West 137, about 3 hours 33 minutes before stops.
- Card Sound Road charges by axle, takes no cash, and gives no discount when towing.
- Every night is at a campground. The county bars RV camping on the US-1 right of way overnight.
How long is the drive down the Overseas Highway in an RV?
The highway runs 113 miles from Key Largo to Key West and crosses 42 bridges, by the Florida Keys tourism council's count. Most rented RVs start further back, on the mainland. From El Monte RV in Princeton, south of Homestead, it is 35 road miles to Key Largo, about 51 minutes. Marathon is 88 miles. Key West is 137 miles, about 3 hours 33 minutes by OSRM routing, before any stop. An RV will take longer than a routing engine says.
One distance nobody official publishes is Florida City to Key West. No FDOT page read gives it. The 113 miles you see quoted is Key Largo to Key West, a different starting point. FDOT District 6 holds the official road record.
The clock matters more than the miles. El Monte hands over weekdays only, with standard pickup after 1 p.m., and several Keys parks close check-in in the late afternoon. If you collect in the afternoon, plan a first night in the Upper Keys. The first-time RV rental guide for the Keys weighs driving down against having a trailer delivered.
What is it like to drive the Seven Mile Bridge in an RV?
Long, and over open water. The bridge is 6.79 miles. Someone rounded up. It carries US-1 west from Marathon toward the Lower Keys, and its west end sits at MM 40 by Monroe County's own numbering.
No source read publishes an RV restriction for the bridge, and there is nowhere to stop on it, so fuel before you start. If you are staying west of it, RV rental on Big Pine Key covers the parks just past the far end, and RV rental in Marathon covers the near side.
What does Card Sound Road cost an RV?
Card Sound Road is tolled by axle, and the rates changed on October 1, 2026. There is no cash lane. You pay by SunPass or get a bill by plate, which adds a $2.50 monthly admin fee. Discount programs do not apply to a vehicle towing a trailer. Here is what that comes to for the rigs people rent for the Keys.
| Rig | Axles | SunPass, one crossing | By plate, one crossing | There and back, SunPass | There and back, by plate |
|---|---|---|---|---|---|
| Motorhome or camper van, 2 axles | 2 | $2.18 | $3.28 | $4.36 | $9.06 |
| Pickup towing a single-axle trailer | 3 | $4.17 | $6.27 | $8.34 | $15.04 |
| Pickup towing a tandem-axle travel trailer | 4 | $5.56 | $8.36 | $11.12 | $19.22 |
| 2-axle motorhome towing a car | 4 | $5.56 | $8.36 | $11.12 | $19.22 |
Worked out from the published rates
- What the source says
- The Card Sound Toll Authority charges by axle, takes no cash, adds a monthly admin fee to plate billing, and bars discounts for a vehicle towing a trailer.
- What it comes to
- A pickup with a tandem-axle trailer pays $5.56 a crossing on SunPass, against $2.18 for a 2-axle motorhome. There and back by plate it is $19.22, against $11.12 on SunPass.
- What to do about it
- Count the axles on the whole rig before you go, and set up SunPass if you will tow. On a rented motorhome, ask the host whether a transponder comes with it and how plate bills are passed on.
- If you do not
- The plate bill, at $8.10 more than SunPass on that tandem trailer trip, arriving after the RV has gone back.
If your route stays on US-1, the table does not apply. If you come down Florida's Turnpike first, its RV tolls by axle are not on the page that was read, so they are not given here. The Keys RV trip cost calculator adds the Card Sound toll to the rental, the site and the tax.
Is there an RV size limit on US-1 or Card Sound Road?
None is published in the sources checked. FDOT District 6 is the agency for US-1, and Monroe County's Card Sound Toll Authority for Card Sound Road. If you are bringing something unusually large, ask them before you rely on silence.
The limits that decide a Keys trip are at the other end: each campground's own cap, and Key West's rule keeping larger RVs off its streets. The Keys campground guides carry each park's figure.
Can you pull over and sleep in the RV along the way?
No. Monroe County code bars camping on the US-1 right of way in the unincorporated county from 11 p.m. to 6 a.m., and a parked RV there in those hours is presumed to be camping. Camping on county-owned property is barred at any hour, parks and beaches included.
No source permits overnight RV parking outside a campground. The rules in Islamorada, Marathon, Layton and Key Colony Beach were not researched, so do not count on them. Key West is about 3 hours 33 minutes from the Princeton pickups by routing, so the answer is to book the night before you set off and drive to it.
What happens on the highway in a hurricane evacuation?
RVs go first. Monroe County's plan for a Category 3 to 5 storm orders non-residents, visitors, RVs and travel trailers out in Phase 1, about 48 hours before tropical-storm winds. Residents follow by zone, and the zones run by mile marker: Zone 2 ends at the west end of the Seven Mile Bridge, Zone 3 covers MM 40 to 63.
The only copy of that wording found is a November 2025 draft amendment to the county's comprehensive plan, and orders for weaker storms are made case by case. Monroe County Emergency Management has the current wording. With a drivable RV, keep it fuelled in season. With a delivered trailer, ask the host who moves it. The hurricane season trip guide covers refunds.
Questions people ask about the drive
Sources
- Florida Keys tourism council, the Overseas Highway
- Florida Keys tourism council, the Seven Mile Bridge
- Card Sound Toll Authority, rates by axle
- Monroe County Code, Chapter 17, Sec. 17-3 and 17-4
- Monroe County comprehensive plan amendment draft, Policy 101.2.4
- El Monte RV, Miami location (pickup hours)
Road miles and drive times are OSRM routing from El Monte RV's Princeton address. The miles are from the Princeton rental lots, the nearest mainland pickup. Most hosts keep their RVs further north in Miami, so the real fee is the host's quote.
Pick the RV for the drive, or skip the drive
Drive a motorhome down yourself, or have a host deliver a trailer to your site and arrive by car. Both start with a campsite booked.