Overseas Highway

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U.S. Highway 1

Overseas Highway
Overseas Highway highlighted in red
Route information
Maintained by FDOT
Length106.5 mi[1][2] (171.4 km)
ExistedJanuary 5, 1928 (1928-01-05)–present
Florida Keys Scenic Highway
Major junctions
South end US 1 / SR A1A in Key West, FL
Major intersections CR 905 in Key Largo, FL
North end US 1 (Dixie Highway) near Florida City, FL
CountryUnited States
Highway system

The Overseas Highway is a 113-mile (181.9 km)[1][2] highway carrying U.S. Route 1 (US 1) through the Florida Keys to Key West. Large parts of it were built on the former right-of-way of the Overseas Railroad, the Key West Extension of the Florida East Coast Railway. Completed in 1912, the Overseas Railroad was heavily damaged and partially destroyed in the 1935 Labor Day hurricane. The Florida East Coast Railway was financially unable to rebuild the destroyed sections, so the roadbed and remaining bridges were sold to the state of Florida for $640,000.

Since the 1950s, the Overseas Highway has been refurbished into a main coastal highway between the cities of Miami and Key West,[3] offering travelers an exotic roadway through a tropical savanna environment and access to the largest area of coral reefs on the U.S. mainland. Many exotic animals such as the American Alligator, American Crocodile and Key Deer inhabit the tropical islands of the Florida Keys.


SR 4A, former designation for the Overseas Highway

While the Overseas Highway today runs along the former Overseas Railroad right of way, portions of the highway came into existence earlier in a different alignment while the railroad was still operational. The concept of an Overseas Highway began with the Miami Motor Club in 1921. The Florida land boom of the 1920s was underway and the club wanted to attract tourists to easily reached fishing areas, which could only be reached by boat or train at the time. The land boom also attracted real estate interests who sought vehicular access to the upper keys where there were thousands of acres of undeveloped land. The completion of the railroad further proved a highway through the keys was feasible.[4]

Construction of the original highway next to Matecumbe railroad station

Construction on the original Overseas Highway, designated State Road 4A (an extension of a route running from Miami to Homestead), lasted through most of the mid 1920s. Officially opening for traffic on January 25, 1928, the original highway existed in two segments at its greatest extent. One segment ran from the mainland via Card Sound Road to Key Largo and extended as far as Lower Matecumbe Key, while a segment in the lower keys existed from No Name Key to Key West. An automobile ferry service connected the 41-mile gap between Lower Matecumbe and No Name Keys.[4] State Road 4A mostly ran alongside of the Overseas Railroad in the upper keys but in the lower keys, it followed a much different path than the railroad and current highway. The ferry landing on No Name Key was located at the end of what is now Watson Boulevard, which carried State Road 4A across No Name Key and Big Pine Key before it crossed to Little Torch Key. On Little Torch Key, it turned south and rejoined the railroad. It would continue along the north side of the railroad to Upper Sugarloaf Key, where it turned south and ran along the current route of County Roads 939 and 939A over Lower Sugarloaf Key and the Saddlebunch Keys. From the Saddlebunch Keys, State Road 4A crossed onto Geiger Key, continuing along what is now Geiger Road and Boca Chica Road. On Boca Chica Key, it followed the shoreline south of Naval Air Station Key West's airstrip to Boca Chica Beach before crossing to Stock Island. On Stock Island, it followed Maloney Avenue and MacDonald Avenue where it rejoined the Overseas Railroad heading into Key West. Most of the State Road 4A bridges in the Lower Keys were of wooden construction and had been in use by the early 1920s.

Interactive Map of the Original Highway segments (red) in relation to the Overseas Railroad/Current Highway (blue). Click to Enlarge.

By the early 1930s it was clear that the ferries were insufficient for the travel needs of the keys, and Monroe County and the State Road Department began making plans to connect the two portions of State Road 4A to make a continuous highway. By 1931, the ferries would also service a 13-mile road built through Marathon on the Vaca Keys with terminals at Hog and Grassy Keys. In 1933, the state legislature created the Overseas Road and Toll Bridge District to seek federal funding to extend the roadways. Funding was scarce as the country was in the midst of the Great Depression, but funding would eventually come through the Federal Emergency Relief Administration, part of President Franklin D. Roosevelt's New Deal. Hundreds of disgruntled World War I veterans seeking early payment of wartime pensions were employed for construction on the roadway and bridges as part of a government relief program.[4]

Eight bridge piers that would have carried the original alignment of the Overseas Highway which can be seen at Mile Marker 73. They serve as a memorial to the veterans who were killed in the Labor Day Hurricane of 1935.

Construction on a bridge connecting Lower Matecumbe Key and Long Key was already underway when the Category 5 Labor Day Hurricane struck Islamorada on September 2, 1935. The hurricane caused widespread damage throughout the area and destroyed much of the Overseas Railroad in the upper keys. Of the over 400 fatalities from the hurricane, more than half were veterans and their families. Their deaths caused anger and charges of mismanagement that led to a Congressional investigation.[5] Just west of Lower Matecumbe Key at Mile Marker 73 on the current highway, eight concrete bridge piers and a small dredged island are all that remains of the veterans' work. The dredged island is now known as Veteran's Key and the piers remain as a tribute to the veterans with a memorial plaque on Craig Key.[6]

Many of the railroad bridges, such as the Bahia Honda Rail Bridge, were retrofitted to accommodate automobile traffic for the Overseas Highway. These bridges were replaced by more modern bridges in the early 1980s.

After the hurricane, the Florida East Coast Railway was financially unable to rebuild the damaged sections of the Overseas Railroad. Seizing a rare opportunity, the state purchased the railroad's entire right of way and remaining infrastructure for a price of $640,000. The Overseas Road and Toll Bridge District abandoned its original highway plans and made new plans to build the highway on the old rail bed from Lower Matecumbe Key to Little Torch Key, effectively connecting the two segments of State Road 4A. The railroad's bridges, which withstood the hurricane and were in good condition, were retrofitted with new two-lane wide concrete surfaces for automobile use. In the case of the Bahia Honda Rail Bridge, which was a truss bridge, the concrete road surface was built on top of the trusses. The conversion of the railroad bridges to automobile use was accomplished by Cleary Brothers Construction Co. of West Palm Beach, and the entire route to Key West was opened to the public in 1938.[7]

Portions of the road were tolled until April 15, 1954; toll booths were located on Big Pine Key and Lower Matecumbe Key. Pigeon Key, roughly the midway point of the Seven Mile Bridge, served as the headquarters for the "Overseas Road and Toll District."[8] The toll for automobiles was $1, plus 25 cents per passenger.[9] The full highway from the mainland to Key West was officially opened for traffic on March 29, 1938 and upon completion, the route became the southernmost segment of U.S. Route 1, which previously terminated in Miami (State Road 4A would remain as a hidden designation until the 1945 Florida State Road renumbering, when the hidden designation became State Road 5).[10] President Franklin D. Roosevelt toured the road in 1939.

The beginning of U.S. 1 in March 1951; U.S. 1 has since been extended to the Monroe County Courthouse in downtown Key West

At this time, the Overseas Highway only ran along the old railroad route in the middle keys; the original highway segments were still in use in the upper and lower keys. As the United States entered into World War II, the U.S. Navy sought improvements to the highway to improve their access from the Naval Air Station on Boca Chica Key to the mainland for national security purposes. The 1920s-era lower keys segment was less than ideal with its winding road and rickety wooden bridges. This resulted in completing the rest of the highway throughout the keys on the former railroad right of way, which the state already owned and was a more direct route with smoother curves that would allow for higher speeds. Also included in this project was the construction of the highway from Florida City to Key Largo on the old railroad route via Jewfish Creek, which shortened the route from Key Largo to the mainland by 17 miles. The new alignments were officially completed on May 16, 1944, with Florida Governor Spessard Holland presiding over ribbon-cutting ceremonies.[11] The original Card Sound Bridge was closed after the Jewfish Creek alignment opened, and its remains were subsequently destroyed by a fire (the Card Sound route would be restored as a secondary route in 1969 with the opening of the current bridge). Today, some segments of the original highway remain as side and frontage roads for the current highway.

Seven Mile Bridge, the longest bridge on the Overseas Highway. The original span crosses over Pigeon Key.
The 106.5-mile (171 km) portion of U.S. 1 in the Keys functions as a National Scenic Byway, named the "Florida Keys Scenic Highway".[12]

The original highway through Key Largo and Tavernier would once again become part of the Overseas Highway in the early 1970s when it was expanded to a four-lane divided highway. Here, the northbound lanes run along the route of the original highway and the southbound lanes along the route of the railroad, which is especially evident in area where the route splits into two one-way streets.[4] The widening was the beginning of a much larger project to rebuild much of the Overseas Highway, which included replacing the aging repurposed railroad bridges with more modern bridges; some of which are able to accommodate more than two lanes of traffic. This included the Seven Mile Bridge, the Bahia Honda Bridge and the Long Key Bridge (although these three original bridges are no longer open to vehicular traffic, they became listed on the National Register of Historic Places in 1979 and are currently used for fishing and pedestrian traffic). The more modern bridges were completed in the early 1980s.

In recent years, Pigeon Key was used by the University of Miami as an oceanography laboratory, but current efforts to restore the buildings on the island have resulted in the establishment of a railroad museum there. The newer Seven Mile Bridge does not have direct access to Pigeon Key; people going there must bike or walk on 2.2 miles (3.5 km) of the Old Seven Mile Bridge from its eastern end on Knight's Key, take a shuttle bus, or take a boat to reach the island.

Mile markers

The Florida Department of Transportation ("FDOT") maintains mile marker signs in the Florida Keys portion of Monroe County along the Overseas Highway (U.S. Highway No. 1). Numbering commences at "0" in Key West, and increases towards the east until Islamorada where the direction changes to the northeast following the Overseas Highway to Key Largo at "106." Outside of the city of Key West and the city of Marathon, street addresses [13] along the Overseas Highway in the Keys correspond to the mile markers. For example, the Tropical Research Laboratory of Mote Marine Laboratory has a physical address of 24244 Overseas Highway. The first two digits indicate that the Laboratory is located at Mile Marker 24 (corresponding to an address on Summerland Key). The next two digits indicate that it is about a quarter of a mile east of the Mile Marker 24 sign (MM 24.24), while the last digit, because it is an even number, indicates that it is located on the gulf side of the Overseas Highway (the term "gulf side" is used in the Middle and Lower Keys as the Overseas Highway runs east-west there; the term "bayside" is used in the Upper Keys where the Overseas Highway runs north-south. All of the Keys use the term "oceanside").

  • The first two-to-three digits denote the Mile Marker, while the next digit denotes the nearest tenth of a mile (e.g., MM 102.5).
  • An address ending in an odd number indicates the location is on the Atlantic or oceanside of the Overseas Highway, while an address ending in an even number indicates the location is on the Florida Bay/Gulf of Mexico or bayside of the Overseas Highway.

Exceptions to this rule do exist, however. There are occasional addresses ending in even numbers on the oceanside and vice versa.


In 2001, the Monroe County Commission, the Florida Department of Environmental Protection's Office of Greenways and Trails, and FDOT entered into a Memorandum of understanding to create the Florida Keys Overseas Heritage Trail (FKOHT).[14] The trail will be a multi-use bicycle and pedestrian facility that will traverse the Florida Keys from Key Largo to Key West. Upon completion, the FKOHT will include an integrated system of educational kiosks, roadside picnic areas, scenic overlooks, fishing piers, water access points, and bicycle and jogging paths. The development of the trail will provide a mechanism for the preservation and use of the historic Flagler Railroad Bridges, 23 of which still exist and are mostly intact. Several alternatives exist for trail alignment, including cutting down the 22-foot-wide (6.7 m), 1940s-era roadway to its original 12-foot (3.7 m) spandrel width, or using the 22-foot-wide (6.7 m) roadway as is, particularly in multi-use areas. In all cases, original bridgework will be repaired or rebuilt, and the breaks created during the 1980s and 1990s fishing pier conversion will be reconnected. Where the original roadway no longer exists, the trail will be temporarily cantilevered on the side of the current US 1 highway bridge, until new 12-foot-wide (3.7 m) trail bridge sections can be built. The new sections will be built to match the historical character of the original bridges.

In popular culture

One of animated television's Wacky Races was The Overseas Hi-Way Race, which first aired on December 28, 1968, on CBS, covering the entire actual route from Key Largo to Key West. While Long Key was correctly portrayed, most of the other in-between keys were given fictional names, and Sombrero Key was actually five miles south of the highway in open water, according to the Florida Keys–East map.

The Overseas Highway is depicted in a screenprint by American artist Ralston Crawford.[15]

An action scene involving a car and fighter jet was filmed on a portion of the old Seven Mile Bridge for the 1994 James Cameron film True Lies. No part of the bridge was destroyed during filming; an 80-foot model of the bridge built off Sugarloaf Key was blown up instead.[16]

Major intersections

Mileposts are taken from US 1, which begins approximately 4 miles (6.4 km) south at an intersection with Whitehead and Fleming streets in Key West.The entire route is in Monroe County.

Key West3.9276.320

US 1 south (North Roosevelt Boulevard) / SR A1A south (South Roosevelt Boulevard) – Business District, Airport, Beaches
US 1 continues south
Bridge over Cow Key Channel
trail on sidewalk to north
Stock Island4.5867.380MacDonald DriveFormer SR 4A
5.2918.515Key Haven BoulevardTo Raccoon Key
Bridge over Boca Chica Channel
Boca Chica Key8.0813.00Naval Air Station Key WestInterchange
Rockland Key8.79014.146Toppino Industrial Drive
East Rockland Key9.18314.779Rockland Drive – NAS Truck EntranceFormer US 1 south
Bridge over Rockland Channel (trail on old bridge to south)
Big Coppitt Key10.69117.205
CR 941 south / Boca Chica Road
Northern terminus of CR 941 (former SR 941)
11.18117.994Shark Key
Bridge over Shark Channel (trail on old bridge to the south)
Saddle Bunch Keys12.547–
Bridge over Saddle Bunch No. 5 (trail on old bridge to the south)
Bridge over Saddle Bunch No. 4 (trail on old bridge to the south)
Bridge over Saddle Bunch No. 3 (trail on old bridge to the south)
14.32823.059Blue Water Drive
Bridge over Saddle Bunch No. 2 (trail on old bridge to the south)
14.96824.089East Circle Drive
Bridge over Lower Sugarloaf Channel (trail on old bridge to the south)
Bridge over Harris Channel
Lower Sugarloaf Key16.95527.286
CR 939 south / Sugarloaf Boulevard
Northern terminus of CR 939 (former SR 939)
Bridge over Harris Gap Channel
Bridge over North Harris Channel
Bridge over Park Channel (trail on old bridge to the south)
Sugarloaf Key19.34931.139Crane Boulevard
CR 939B south
Old SR 4A; northern terminus of CR 939 (former SR 939)
Bridge over Bow Channel (trail on old bridge to the south)
Cudjoe Key21.40934.454Blimp Road
Bridge over Kemp's Channel (partial old bridge to the south)
Summerland Key25.19740.551
CR 942 south / East Shore Drive
Bridge over Nile's Channel (partial old bridge to the south)
Ramrod Key27.26443.877Indies Road
Bridge over Torch Ramrod Channel
Middle Torch Key27.83644.798Middle Torch Road – Big Torch Key
Bridge over Torch Key Channel
Little Torch Key28.21645.409State Road 4AFormer SR 4A
Bridge over South Pine Channel (partial old bridge to the south)
Bridge over North Pine Channel
Big Pine Key30.52749.128
CR 940 north / Key Deer Boulevard – National Key Deer Visitor Center
Southern terminus of CR 940 (former SR 940)
Bridge over Spanish Harbor Channel
Bahia Honda Bridge over Bahia Honda Channel (partial old bridge to the south)
Bahia Honda Key36.79459.214Bahia Honda State Park
Bridge over Ohio Bahia Honda Channel (trail on old bridge to the north)
Ohio Key38.7562.36no major intersections
Bridge over Missouri Ohio Channel (trail on old bridge to the north)
Bridge over Little Duck Missouri Channel (trail on old bridge to the north)
Little Duck Key39.82364.089Veterans Memorial Park
Seven Mile Bridge over Moser Channel (partial old bridge via Pigeon Key to the north)
Marathon47.18675.939Knights Key
Marathon (Vaca Key)48.05977.343
CR 931 north (20th Street)
Southern terminus of CR 931 (former SR 931)
CR 931 south / Sombrero Beach Road – Sombrero Beach
Northern terminus of CR 931 (former SR 931)
Bridge over Vaca Cut
trail on sidewalk to north
Marathon (Fat Deer Key)53.61086.277Sadowski CausewayKey Colony Beach
Marathon (Long Point Key)56.19190.431Curry Hammock State Park
Marathon (Crawl Key)56.45990.862Banana Boulevard
Marathon (Grassy Key)57.59492.689Kyle Avenue
Bridge over Tom's Harbor No. 4 (trail on old bridge to the south)
Duck Key61.05198.252Hawks Cay
Bridge over Tom's Harbor Cut (trail on old bridge to the south)
Conch Key62.846101.141North Conch Avenue
Long Key Bridge over Long Key Channel (trail on old bridge to the south)
Long Key67.404108.476Long Key State Park
Bridge over Channel No. 5 (partial old bridge to the north)
Craig Key72116no major intersections
Bridge over Channel No. 2 (trail on old bridge to the north)
Islamorada (Lower Matecumbe Key)74.403119.740Gulfview Drive
Bridge over Lignumvitae Channel
Bridge over Indian Key Channel
Bridge over Tea Table Channel
Bridge over Tea Table Relief
Islamorada (Upper Matecumbe Key)80.425129.431Frontage RoadFormer SR 4A
83.509134.395Frontage RoadFormer SR 4A
Bridge over Whale Harbor Channel
Snake Creek Bridge over Snake Creek
Islamorada (Plantation Key)90.513145.667Plantation Avenue / Sunshine Boulevard / Bessie Road
Bridge over Tavernier Creek Waterway
Tavernier91.485147.231Ocean Boulevard
Key Largo103.430–
Bridge over Marvin D. Adams Waterway
CR 905 north (Card Sound Road) – Miami
Old SR 4A; Southern terminus of CR 905 (former SR 905)
US 1 north (Dixie Highway)
US 1 continues north to Florida City, Homestead, and Miami
1.000 mi = 1.609 km; 1.000 km = 0.621 mi


  1. ^ a b Logan, Walter (January 30, 1983). "ACROSS 42 BRIDGES THROUGH FLORIDA'S KEYS". The New York Times. Florida. Retrieved July 19, 2015.
  2. ^ a b "Road Trip: Florida Keys - National Geographic". Travel.nationalgeographic.com. January 1, 1970. Retrieved July 19, 2015.
  3. ^ Marzyck, Marion E. "History and Background: The Overseas Highway". Web World Wonders. Florida State University. Archived from the original on May 1, 2008. Retrieved October 3, 2011.
  4. ^ a b c d History of Overseas Highway
  5. ^ Investigative Files Regarding the Labor Day Hurricane of 1935 , ca. 1935 - 1968. Record Group 15: Records of the Department of Veterans Affairs, 1773 - 2007. Retrieved January 2, 2022.
  6. ^ Wilkinson, Jerry. "The Bridge That Never Was". Keys Historeum. Retrieved January 9, 2015.
  7. ^ Crestview, Florida, "To Build Highway", Okaloosa News-Journal, Friday May 1, 1942, Volume 28, Number 15, page 5.
  8. ^ Pigeon Key—Headquarters for the Overseas Road and Toll District, c. 1952 (Photograph). Historical Preservation Society of the Upper Keys. Retrieved October 3, 2011.
  9. ^ Wilkinson, Jerry. "History of the Overseas Highway". Historical Preservation Society of the Upper Keys. Retrieved October 3, 2011.
  10. ^ Sanderson, Dale. "End of US highway 1". U.S. Ends. Archived from the original on September 15, 2015. Retrieved September 9, 2015.
  11. ^ Hopkins, Alice. "The Development of the Overseas Highway" (PDF). FIU Digital Collections. Florida International University. Retrieved June 30, 2015.
  12. ^ "National Scenic Byways & All-American Roads: Florida Keys Scenic Highway". America's Byways. Washington D.C.: U.S. Department of Transportation: Federal Highway Administration. Retrieved February 10, 2023.
  13. ^ Wilkinson, Jerry. "Mile Markers in the Florida Keys". Historical Preservation Society of the Upper Keys. Retrieved August 9, 2006.
  14. ^ "Florida Keys Overseas Heritage Trail". Florida Keys Overseas Heritage Trail. Archived from the original on October 9, 2011. Retrieved October 3, 2011.
  15. ^ Overseas Highway Whitney Museum of American Art.
  16. ^ "Don't Worry: Seven Mile Bridge Remains Intact".
  17. ^ FDOT straight line diagrams Archived March 6, 2014, at the Wayback Machine, accessed April 2014

External links