Original route to Tampa Original plans for I-75 called for its southern terminus to be in
Tampa, where it would terminate at
I-4 (at the current interchange between I-4 and I-275, with I-4, which was completed in the Tampa Bay area by 1962, continuing west along what is now I-275 over the
Howard Frankland Bridge into
St. Petersburg). Plans for I-75 from Tampa to
Sault Ste. Marie, Michigan, were authorized as part of the
Federal-Aid Highway Act of 1956, signed into law by President
Dwight D. Eisenhower, which created the
Interstate Highway System. Construction of the original route from the Georgia border to Tampa via
Gainesville and
Ocala lasted through most of the 1960s. The first segment of I-75 to open in Florida was from the Georgia border to SR 6 just south of
Jennings, which opened in 1963. It would reach
US 90 in Lake City later that year. By mid-1964, I-75 opened from Lake City to the newly completed
Florida's Turnpike (known then as the Sunshine State Parkway) in
Wildwood. Segments of the original route that are now part of I-275 near Tampa would begin opening in 1966, and construction of the full route would be completed by 1969.
Extension to Miami Due to major growth in
Southwest Florida (particularly Fort Myers and Naples), it was becoming clear that this part of the state would soon need a freeway. Florida's state government first proposed to build a West Coast Turnpike in 1964 from the Tampa Bay area south to Naples. Plans for the West Coast Turnpike (which would have been tolled) were canceled in 1968, when it was announced that US Secretary of Transportation
Alan S. Boyd had approved an extension of I-75 south to Naples and then east to Miami. The federal government would pay for 90 percent of the extension using funds allocated by the
Federal-Aid Highway Act of 1968, which was signed into law by President
Lyndon B. Johnson. In preparation for the extension, I-75's designation was extended along the preexisting route of I-4 over the
Howard Frankland Bridge into St. Petersburg by the end of 1969 (I-4's designation would be truncated to its current terminus at this time). From St. Petersburg, I-75 was proposed to continue south over the
Sunshine Skyway Bridge and continue south along a new freeway roughly parallel to the
Tamiami Trail (
US 41) along the lower Gulf Coast to Naples. As the extension was planned in 1968, plans were also made for a freeway bypassing Tampa Bay to the east. The bypass was initially planned to be designated
Interstate 75E (
I-75E), and was to split from I-75 near
Wesley Chapel and rejoin it just north of
Ellenton. However, in 1972, it was determined that maintaining the main route of I-75 through Downtown Tampa would eventually require major improvements to the existing infrastructure to handle through traffic. Additionally, neither the 1954 nor 1971 spans of the original Sunshine Skyway Bridge were up to
Interstate Highway standards as they both lacked shoulders. As a result, it was decided that I-75 would be re-routed and instead follow the bypass route. FDOT could have renumbered I-75E into what could have possibly been
Interstate 75W (
I-75W), but, due to a 1973-based
American Association of State Highway and Transportation Officials (AASHTO) rule indicating that suffixed routes were to be renumbered to reduce motorist confusion, the option of renumbering I-75E into I-75W was scrapped, with the I-75E designation instead being renumbered to what is known today as I-275, and both the I-75 and I-275 designations were swapped into their current configuration in 1973. I-75 reached as far south as 38th Avenue North in St. Petersburg when the designations were switched. Despite the designation switch, both freeways' hidden designations still reflect the originally planned routing, with I-75's SR 93 designation following I-275, and the current route of I-75 on the bypass being designated SR 93A. Construction on the bypass segment of I-75 began in 1979. The initially favored proposal for I-75 to reach Miami from Naples was to have I-75 run along the Tamiami Trail (US 41) across the Everglades to just east of the
SR 826 (Palmetto Expressway) where it would continue along
SR 836 (Dolphin Expressway) and terminate at
I-95 and
I-395 in
Downtown Miami. However, in 1973, planners made the decision to shift I-75's proposed route to cross the Everglades along Alligator Alley over environmental concerns related to upgrading the Tamiami Trail, which runs along the northern border of
Everglades National Park. Additionally, Alligator Alley itself needed upgrading, as the then-narrow
toll road was dangerous to both motorists and wildlife (most notably the
Florida panther) alike, and the Dolphin Expressway, with its left exits and narrow lanes, was not being built to
Interstate Highway standards, with the costs to upgrade it being too expensive. By using this route, I-75 would run along the alley to the proposed Port Everglades Expressway, where it would turn south along a new freeway through the western suburbs of
Weston and
Pembroke Pines to Miami. It was still planned to continue east to I-95, but, due to local opposition, I-75 was not built past its current terminus at SR 826 (Palmetto Expressway) in
Hialeah. With this new route, the Port Everglades Expressway was then planned to be built as an Interstate Highway designated
I-595 to provide an Interstate connection between I-75 and I-95. The first piece of the south extension of I-75 to open was a short segment just east of Fort Myers from SR 78 south to Corkscrew Road in 1979. This piece would extend north to Tucker's Grade just south of Punta Gorda in early 1980 and south to Immokalee Road in North Naples by 1981. Also in 1981, the segment from US 301 in
Manatee County south to River Road near Venice opened, which would be completed south to the southern segment in
Punta Gorda later that year. It would reach Alligator Alley in Naples by 1984. The route from Tampa to Naples would be complete by 1986 as segments of the Tampa bypass were opened from 1982 to 1986. In the Miami area, I-75 was opened from US 27 to its terminus at the Palmetto Expressway in 1986.
Alligator Alley The Alligator Alley segment of I-75 extends from a
toll plaza just east of
Naples to an interchange with I-595 and the Sawgrass Expressway (SR 869) in Sunrise just west of
Fort Lauderdale. The highway previously existed as a two-lane tollway connecting the two coasts of Florida. Initially known as the Everglades Parkway (
SR 84), it opened for traffic on February 11, 1968, after four years of construction. Built by H. L. Mills Construction Company, it had been called the most controversial roadway ever built in Florida during its initial construction. The name "Alligator Alley" was given by the
American Automobile Association (AAA) while it was being planned as they believed it would be useless to cars and merely an "alley for
alligators". As alligators frequent the waterways beside the road, and occasionally the roadway itself, the nickname developed a literal meaning. The state moved to officially adopt the "Alligator Alley" name in August 1966. This helped to reduce the
environmental impact of the highway, especially upon the severely
endangered Florida panther. The completion of the converted Alligator Alley was the final link of the I-75 extension. The segment was signed I-75 on November 25, 1992, completing the highway from Miami to
Sault Ste. Marie, Michigan.
Recent history In May 1999, the East Toll Plaza was converted to serve only northbound traffic, while the West Toll Plaza was converted to serve only southbound traffic. This was done to reduce congestion. In January 2000, the West Toll Plaza of Alligator Alley was dedicated to the memory of Edward J. Beck, a toll collector who was murdered on the job on January 30, 1974. In January 2002, FDOT transitioned existing interchange exit numbers on all Interstate Highways from sequential exits to mileage-based exits. In April 2008, FDOT proposed leasing a section of road to private operators. The additional revenue the state would receive was one of primary motives to
privatize this section of Alligator Alley. However, the motion failed in May 2009 when no bids were received that met the required terms. In fall 2016, a six-lane widening was completed between Sumter Boulevard and North River Road. FDOT contracted Prince Contracting in 2015 to construct the state's first
diverging diamond interchange at the
University Parkway (exit 213) interchange. The $74.5-million (equivalent to $ in ) project started construction in August 2015 and completed in September 2017. The interchange handles more than 80,000 vehicles per day and reduced intersection delays by 50 percent. FDOT implemented express lanes along of the I-75 and SR 826 (Palmetto Expressway) corridors, from just south of the SR 836 (Dolphin Expressway), in
Miami-Dade County, to I-595 in
Broward County. The project completed another section of the South Florida managed lanes network, benefiting all motorists by improving mobility, relieving congestion, providing additional travel options, and accommodating future growth in the area. The 75 Express Lanes project extends along I-75 from Northwest 170th Street in Miami-Dade County to I-595 in Broward County. Work was completed in four segments to minimize the effects on the public. Construction began in early 2014 and was completed in 2018. The total project cost $481 million (equivalent to $ in ). In 2015, the
Central Florida Expressway Authority (CFX), FDOT, and
FTE announced a $68.5-million (equivalent to $ in ) project to make several improvements to I-75's interchange with SR 44 (exit 329) and the adjoining interchange with Florida's Turnpike (exit 328). This included adding a
collector–distributor ramp in each direction along I-75 leading to the interchange northbound, and leading from SR 44 to the southbound Turnpike, as well as widening I-75 to six lanes in each direction leading to the interchange, and adding another access point from the northbound Turnpike to SR 44 (exit 307). The project, which was handled by Middlesex Construction, began construction in September 2016. The new northbound offramp to SR 44 was completed on September 19, 2019, and the new southbound onramps to the Turnpike and I-75 were completed in early November 2019. The project overall was completed in January 2020. Another diverging diamond interchange with
SR 56 (exit 275) was initially proposed in May 2018; construction on the revamped intersection began in February 2019, and it was completed in 2022. An additional interchange was planned for Overpass Road north of
SR 54, connecting to
CR 530. The interchange opened to traffic the morning of January 18, 2023. Another diverging diamond interchange with Northwest 49th Street in Ocala (exit 356) was initially proposed in November 2020. The project, which is projected to cost $147.9 million, is scheduled to begin construction in June 2025. ==Services==