||This article needs additional citations for verification. (April 2007)|
|Length:||1,786.47 mi (2,875.04 km)|
|South end:||SR 826 / SR 924 in Hialeah, FL|
I-4 near Tampa, FL
|North end:||Canadian border on Int'l Bridge in Sault Ste. Marie, MI|
Interstate 75 (I-75) is a major north–south Interstate Highway in the Great Lakes and Southeastern regions of the United States. It travels from State Road 826 (Palmetto Expressway) and State Road 924 (Gratigny Parkway) in Hialeah, Florida (northwest of Miami) to Sault Ste. Marie, Michigan, at the Ontario border. Interstate 75 is the seventh longest interstate highway after Interstate 95 and passes through six different states: Florida, Georgia, Tennessee, Kentucky, Ohio and Michigan.
Due to traffic levels on the Interstate, much of the route is six lanes even in rural areas. The longest continuous segment of six-lane (or more) roadway in the U.S. is along I-75 from the Florida's Turnpike junction in Wildwood, Florida to I-24 in the Chattanooga area, using I-475 to bypass Macon, Georgia, though this long stretch has an exception to its 3 lanes or more continuity around the I-75/I-475 split where it is 2 lanes on each side for only a few miles.
Route description 
Interstate 75 starts at an interchange with State Road 924 and State Road 826 in Hialeah, a suburb of Miami. After an intersection with the Homestead Extension of Florida's Turnpike and an interchange with Interstate 595 and the Sawgrass Expressway, the interstate leaves the Miami metropolitan area and turns westward to travel through the Everglades along the tolled Alligator Alley, which brings the highway to the Gulf Coast and Naples, where it again heads north. Passing through Bonita Springs, Fort Myers, and Sarasota, Interstate 75 encounters a series of construction projects that will increase the lane count from two lanes in each direction to three in each direction. The freeway enters the Tampa Bay metropolitan area before the interchange with Interstate 275 northbound, which handles St. Petersburg-bound traffic. Within the Tampa metro are three more major junctions: One with the Lee Roy Selmon Expressway which carries traffic into downtown Tampa; one with Interstate 4 which carries traffic across the center of the state to the East Coast; and another as Interstate 275 traffic defaults back onto northbound. The freeway proceeds to enter suburban portions of Pasco, Hernando, and Sumter counties on its way to Ocala and Gainesville. At Lake City, Florida, the Christopher Columbus Transcontinental Highway, Interstate 10, intersects with Interstate 75, providing routes toward Jacksonville, Florida; Tallahassee; Mobile, Alabama; New Orleans, Louisiana; and points westward. Afterward, the northmost stretch of Interstate 75 in Florida exits the Sunshine State into southern Georgia.
Interstate 75 enters Georgia near Lake Park, and it continues northward through the towns of Valdosta, Tifton and Cordele until it reaches the Macon area, where it intersects with Interstate 16 eastbound towards Savannah. For northbound traffic wishing to avoid potential congestion in Macon, Interstate 475 provides a relatively straight bypass west of that city and Interstate 75's route. After Macon it passes the small town of Forsyth. The freeway reaches no major junctions again until in the Atlanta metropolitan area. The first metropolitan freeway met is Interstate 675, then followed by the Atlanta "Perimeter" bypass, Interstate 285. It crosses inside the Perimeter and heads north several miles towards the Atlanta city center. Interstate 75 is then duplexed with Interstate 85 due north over the Downtown Connector through the central business district of Atlanta. After the two Interstates split, Interstate 75 makes a beeline northwest, crossing outside the Interstate 285 Perimeter and heading towards the major suburban city of Marietta. This section of Interstate 75 just north of Interstate 285 has 15 through lanes. North of Marietta, the final major junction in the Atlanta metropolitan area is the Interstate 575 spur. Interstate 75 then traverses the hilly northwestern Georgia terrain as it travels towards Chattanooga, Tennessee.
The freeway enters Tennessee directly in the Chattanooga metropolitan area, where it intersects with Interstate 24. Exiting Chattanooga to the northeast, Interstate 75 passes through an area known for dense fog. Twelve people were killed and 42 were injured in a 99 vehicle accident on that stretch of I-75 in heavy fog on December 11, 1990. Interstate 75 does not meet any other highways until it is multiplexed with Interstate 40 and heads eastbound. Together, they enter the outskirts of Knoxville, where Interstate 75 multiplexes itself with a different road, this time Interstate 640, but only for a short time. When the two meet Interstate 275, Interstate 75 becomes its own freeway and heads north towards the Kentucky border. On the journey northward from Knoxville to the Kentucky border, interstate 75 encounters some of its highest points of elevation through the Cumberland Mountains and Cumberland Plateau region, cutting through the uppermost peaks and ridges of the mountains.
Interstate 75 continues northbound through the hilly, rugged terrain of the Cumberland Plateau region of Kentucky passing through London and Richmond, eventually reaching Lexington, where it briefly runs coterminously with Interstate 64 before splitting off for Cincinnati, Ohio. Near Walton, Interstate 71 merges with Interstate 75, making for yet another multiplexed portion of freeway. Interstate 275, which is the Cincinnati beltway, is then intersected by Interstate 71/75. After passing through Covington, the freeway crosses the Ohio River via the lower level of the Brent Spence Bridge and continues into Cincinnati.
Immediately after entering Cincinnati, Interstate 71 separates from Interstate 75, taking a more easterly routing through the city, while Interstate 75 remains generally northbound throughout the metropolitan area. Interstate 74 westbound, Ohio State Route 562 eastbound, and Ohio State Route 126 all intersect the freeway as it makes its way northward. In Arlington Heights, a Cincinnati suburb, Interstate 75 sees a carriageway split for a few miles. After another interchange with the Interstate 275 beltway, the freeway continues in the metropolitan area, passes through Middletown and heads toward Dayton, where Interstate 675, Interstate 70, and U.S. Route 35, have interchanges. The intersection of Interstate 75 with Interstate 70 is known as the Freedom Veterans Crossroads. After exiting the city of Dayton, Interstate 75 makes its way northbound through Ohio, passing through the smaller cities of Wapakoneta, Lima, Findlay and Bowling Green before finally reaching Toledo, located on the Michigan border. Interstate 475 is met first south of the city, and then the cross-country highways of Interstate 80/Interstate 90/Ohio Turnpike. Interstate 475 then meets with 75 again. Interstate 280 is the last major junction in Ohio; the freeway crosses into Michigan soon afterward.
Interstate 75 hugs the western shore of Lake Erie upon entering Michigan—until about Monroe, when it heads north eastward and prepares to enter Detroit and its surrounding suburbs. Yet another I-275 is met as the freeway goes deeper into the Detroit metropolitan area, and no other major junctions are present until downtown. Once downtown, Interstate 75 meets the Ambassador Bridge to Windsor, Ontario, Interstate 375 (Chrysler Freeway), I-94, I-96, M-10 and M-8 (Davison Freeway). I-696 also intersects I-75 in the northern metro area. When the freeway reaches Pontiac, there is a junction with M-59; and further north in Flint, the interstate meets I-475 and I-69. The freeway then heads north towards Saginaw, where I-675 acts as a spur route into the city. Further north in Bay City, the major junction of US 10 exists, providing access to Midland as well as downtown Bay City. The last major interchange occurs at 4 Mile Road just south of Grayling where US 127 northbound ends with traffic merging onto northbound I-75 and the southbound starts taking drivers through the center of the state granting easier access to cities such as Clare, Mt. Pleasant, Lansing, and Jackson. At Mackinaw City, I-75 crosses the Mackinac Bridge to reach the Upper Peninsula. It is the only Interstate located in the Upper Peninsula of Michigan, and it continues until the Canadian border in Sault Ste. Marie, at the International Bridge.
This limited access highway that was planned in the 1950s roughly follows the general route of many older at-grade highways, including U.S. Route 2, U.S. Route 27, U.S. Route 25, and U.S. Route 41, among others. Some of these older U.S. Routes (several of which are still in existence) previously had replaced the eastern route of the old Dixie Highway.
Interstate 75 was planned to end in Tampa, Florida, in the original plan for 41,000 miles of interstate highways. However, beginning in the 1960s, there was a huge growth in the population of southwestern Florida (Sarasota, Ft. Myers, Naples, Cape Coral, etc.), hence the need for new highways, especially a north-south expressway, as well as one connecting Florida's Gulf Coast to South Florida. At first, Florida state legislators proposed a toll in the new highway, but by 1968, it was decided that the Federal Government would pay 90% towards the extension of I-75 to southwestern and southeastern Florida. This included subsuming a toll highway from Naples to the Fort Lauderdale area, the Alligator Alley, and furthermore to connect this expressway with Interstate 95 in North Miami—though due to some local opposition, I-75 presently ends a few miles short of I-95.
On December 21, 1977, I-75 was completed from Tampa to Sault Ste. Marie with its final segment opening between northern Marietta, Georgia, and Cartersville, Georgia. Then the final stretch of Interstate 75 in South Florida was completed in 1986 in Miami-Dade County and Broward County, but the last stretch to receive the signs for I - 75 was the reconstructed (rebuilt and widened) Alligator Alley on November 25, 1992.
Major intersections 
- Homestead Ext of Florida's Turnpike near Miami Lakes
- I-595 in Davie, serving Fort Lauderdale-Hollywood International Airport
- SR 80 near Fort Myers
- I-275 near Parrish
- SR 60 near Brandon
- I-4 near Tampa
- I-275 near Lutz
- I-10 in Lake City
- I-475 around Macon (twice).
- I-16 in Macon
- I-675 near Stockbridge
- I-285 outside Atlanta (loop around the city), on the southeast side in Clayton County and on the northwest side near Marietta (twice)
- I-85 in Atlanta. They stay connected for several miles through downtown on a highway known as the Downtown Connector.
- I-20 in Atlanta
- I-575 near Kennesaw
- I-24 in Chattanooga
- I-40 near Lenoir City. They stay connected until Knoxville.
- I-64 in Lexington. They stay connected for 6 miles (9.7 km) to the east of downtown Lexington.
- I-71 in Walton. They stay connected until Cincinnati, Ohio.
- I-275 in Erlanger (loop around Cincinnati), and again in Sharonville, Ohio
- I-74 in Cincinnati
- I-675 in Miamisburg
- I-70 in Vandalia, Ohio
- I-80 (Ohio Turnpike) / I-90 in Rossford
- I-475 in Perrysburg and Toledo
- I-280 in Toledo, Ohio
- I-275 in Newport
- I-96 (Jeffries Freeway) in Detroit
- M-10 (Lodge Freeway) in Detroit
- I-375 in Detroit
- I-94 (Edsel Ford Freeway) in Detroit
- M-8 in Detroit
- I-696 (Walter P. Reuther Freeway) north of Detroit
- I-69 in Flint
- I-475 in Flint
- I-675 in Saginaw
- US 10 west of Bay City
- US 127 south of Grayling
- US 31 south of Mackinaw City
- US 23 in Mackinaw City
- US 2 in St. Ignace
Auxiliary routes 
- Tampa, Florida/St. Petersburg, Florida - I-175 (1.294 mi/2.08 km), I-275 (63.387 mi/102.01 km), I-375 (1.220 mi/1.96 km)
- Macon, Georgia - I-475
- Atlanta, Georgia - I-675
- Suburban Spur to Canton, Georgia, I-575 in the Atlanta area
- Knoxville, Tennessee - I-275
- Knoxville, Tennessee - I-640
- Cincinnati, Ohio - I-275
- Dayton, Ohio - I-675
- Toledo, Ohio - I-475
- Detroit, Michigan - I-275, I-375
- Flint, Michigan - I-475
- Saginaw, Michigan - I-675
- DeSimone, Tony (October 31, 2002). "Table 1: Main Routes of the Dwight D. Eisenhower National System Of Interstate and Defense Highways as of October 31, 2002". Route Log and Finder List. Federal Highway Administration. Retrieved October 2, 2007.
- Obenberger, Jon; DeSimone, Tony. "Dwight D. Eisenhower National System of Interstate and Defense Highways: Interstate System Facts". Federal Highway Administration. Retrieved February 2008. "I-75, Miami, FL to Sault Ste Marie, MI"
- Staff (October 28, 1992). "Safety Recommendation in reply to H-92-92" (PDF). National Transportation Safety Board. Retrieved December 28, 2008.
- Keeter, Brian (October 25, 2004). "Nation's Top Highway Official Dedicates Key Dayton, Ohio, Interstate Interchange to State's Military Personnel" (Press release). Federal Highway Administration. Retrieved March 26, 2011.
- "West Coast Turnpike Study Ordered By Kirk". St. Petersburg Times. April 20, 1967. p. 1B.
- "I-75 Extension Should Kill Toll Road - Cramer". Daytona Beach Morning Journal. August 16, 1968. p. 16.
- Staff. "Previous Interstate Facts of the Day". Celebrating the Eisenhower Interstate Highway System. Federal Highway Administration. Retrieved May 11, 2010.
- Rand McNally (2005). The Road Atlas (Map) (2005 ed.). ISBN 9780886408473.
- Transportation Statistics Office. "GIS Data / Map Directory". Florida Department of Transportation. Archived from the original on February 6, 2007.
- Pavement Management Office (February 2, 2007). "Pavement Management Reports". Florida Department of Transportation. Archived from the original on February 3, 2007.
- Office of Transportation Data (2003) (PDF). Interstate Mileage Report (438 Report) (Report). Georgia Department of Transportation. http://www.dot.state.ga.us/DOT/plan-prog/transportation_data/400reports/2003/dpp438_2003.pdf.
|Wikimedia Commons has media related to: Interstate 75|
- Geographic data related to Interstate 75 at OpenStreetMap
- Interstate 75 at Michigan Highways
- Interstate 75 on Cincinnati-Transit.net