If you’ve ever spent four hours staring at the bumper of a semi-truck in the middle of Georgia, you’ve probably asked yourself: where does I-75 start and end, and why does it feel like it never stops?
It’s one of those massive, concrete arteries that defines the American East. It cuts through the heart of the country, moving everything from Florida oranges to Michigan-made car parts. It’s nearly 1,800 miles of asphalt. That is a lot of gas station coffee.
Most people think of it as the "vacation highway" or the "snowbird express." And honestly, it is. But the actual physical points where the road begins and terminates are surprisingly specific, and if you aren't paying attention, you'll miss them entirely.
The Southern Terminus: Hialeah’s Humidity
Down south, Interstate 75 doesn’t end with a dramatic cliffside view or a bridge to the Caribbean. It ends in a sprawl of concrete in Hialeah, Florida. Specifically, the southern terminus is at the intersection with State Road 826 (the Palmetto Expressway) and State Road 924 (the Gratigny Parkway).
It’s Miami-Dade County. It’s loud. It’s hot.
If you are driving south, the interstate basically dissolves into the local expressway system of the Miami metropolitan area. Most travelers heading to the actual beaches or the Keys will have hopped off long before this point, but for the purists, this is the official "Mile 0."
Back in the early planning stages of the Interstate Highway System, there was actually a lot of debate about where I-75 should go. Some early maps didn't even have it reaching Miami. However, the Federal Aid Highway Act of 1956 changed the landscape of the country forever, and by the late 1960s, the extension into South Florida was a go.
Interestingly, the stretch between Naples and Fort Lauderdale—popularly known as Alligator Alley—wasn't originally part of I-75. It was a two-lane toll road. It was dangerous. People called it one of the most boring and hazardous drives in the country because if you went off the road, you were literally in a swamp with the gators. When it was upgraded to interstate standards in the 80s and 90s, it finally linked the Gulf Coast to the Atlantic side, completing the southern leg of the route.
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The Northern Terminus: The Canadian Gateway
At the other end of the world—or at least it feels that way if you’re driving the whole thing—is Sault Ste. Marie, Michigan. This is the northern terminus.
It ends at the Sault Ste. Marie International Bridge.
Once you hit the end of I-75 North, you are looking at Ontario, Canada. There is no more road left in the United States. You either go through customs or you turn around and head back toward the Mackinac Bridge.
The contrast between the two ends is jarring. In Hialeah, you have palm trees and 90-degree humidity. In the "Soo" (as the locals call it), you have Lake Superior winds and snow that can pile up higher than your SUV.
The northern section of I-75 in Michigan is particularly famous for the Mackinac Bridge. Spanning five miles, it connects Michigan’s Lower and Upper Peninsulas. When it opened in 1957, it was a marvel of engineering. Even today, it remains one of the longest suspension bridges in the world. Driving across it on a windy day is... an experience. The authorities actually have drivers who will take your car across for you if you're too terrified to do it yourself. Seriously. It’s a real service.
Why the Route Matters: More Than Just Miles
You can’t talk about where I-75 starts and ends without talking about what happens in the middle. It’s the second-longest north-south interstate in the U.S. (after I-95).
It passes through six states:
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- Florida
- Georgia
- Tennessee
- Kentucky
- Ohio
- Michigan
Each state uses the road differently. In Georgia, I-75 is the lifeblood of Atlanta. If you've ever been caught in "The Connector" where I-75 and I-85 merge through downtown, you know true patience. Or true rage. Probably both.
In Tennessee and Kentucky, the road becomes something else entirely. It cuts through the Cumberland Plateau and the Appalachian foothills. The elevation changes are significant. If you’re driving a heavy rig or towing a trailer, your brakes are going to feel it near Jellico, Tennessee. The "Jellico Mountain" stretch is notorious among truckers for its steep grades and unpredictable winter weather. One minute it’s raining, the next you’re in a whiteout.
Misconceptions About the Start and End Points
A common mistake people make is thinking I-75 starts in Tampa. It doesn't. While Tampa is a major hub and the interstate makes a massive sweep through the Gulf Coast, it continues for miles further south through the Everglades.
Another weird quirk? The "gap" that used to exist. For years, I-75 wasn't a continuous ribbon of pavement. In parts of Georgia and Florida, there were huge unfinished sections where you had to divert onto local U.S. highways. It wasn't until the 1980s that the entire route was truly "finished" to interstate standards from end to end.
Then there’s the Ohio stretch. People often get confused near Cincinnati because the road crosses the Ohio River on the Brent Spence Bridge. It’s a double-decker bridge that carries both I-75 and I-71. It is also one of the most congested freight corridors in the entire country. If you're looking for the "middle" of the journey, this is basically it. You're leaving the South and entering the industrial Midwest.
The Evolution of the Road
The route hasn't always looked like this. Before the interstates, people used U.S. Route 25 and U.S. Route 41 to make this trip. If you look at a map, I-75 largely parallels these older roads.
U.S. 41 was the original "Dixie Highway." It was the road that first brought tourists to Florida in the 1920s. When I-75 was built, it basically killed the small-town economies that relied on U.S. 41 traffic. Now, those towns are just blips you see from the exit ramps, usually marked by a Cracker Barrel or a Buc-ee’s.
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Real-World Stats for the Curious
If you are planning to drive from the start in Hialeah to the end in Sault Ste. Marie, here is what you are actually looking at:
- Total Distance: Approximately 1,786 miles.
- Drive Time: Roughly 26 to 28 hours of pure driving, assuming no major accidents in Atlanta or Cincinnati.
- Major Cities: Miami, Tampa, Atlanta, Chattanooga, Knoxville, Lexington, Cincinnati, Dayton, Toledo, Detroit, Flint.
- Highest Point: Near the Tennessee-Kentucky border, reaching elevations over 2,000 feet.
Most people don't do the whole thing. It’s a brutal drive. But for those who do, you witness a slow-motion transition of the American landscape. You go from the subtropical marshes of the Everglades to the pine forests and rocky outcrops of the Great Lakes.
Practical Advice for I-75 Travelers
If you’re actually going to tackle a significant portion of this road, don't just wing it.
First, Atlanta is a beast. Avoid it between 6:30 AM and 10:00 AM, and again from 3:30 PM to 7:00 PM. If you hit it at 5:00 PM on a Friday, just accept your fate. There is an HOV lane, but even that gets choked.
Second, mind the weather in the mountains. Tennessee and Kentucky police are very quick to shut down sections of I-75 if ice starts to form on the bridges. If you see signs for "Fog Area," take them seriously. The fog in the Hiwassee River area in Tennessee can drop visibility to near zero in seconds.
Third, gas up before the Alley. If you’re heading south and entering Alligator Alley (the stretch between Naples and Weston/Fort Lauderdale), make sure you have fuel. There is only one recreation/service plaza in the middle of that 75-mile stretch. If you run out of gas there, you’re waiting a long time for a very expensive tow.
Final Logistics
To summarize the journey:
Start at SR 826/SR 924 in Hialeah, Florida.
End at the International Bridge in Sault Ste. Marie, Michigan.
It is a massive undertaking of engineering that connects the palm trees to the permafrost. Whether you're moving freight or just trying to get to Disney World, I-75 is the backbone of the eastern United States.
Next Steps for Your Trip
If you are planning to drive the full length, download a real-time traffic app like Waze or Google Maps specifically to monitor the "hot zones" in Atlanta and Cincinnati. Check the Michigan Department of Transportation (MDOT) website if you're traveling in winter, as lake-effect snow frequently closes lanes near the northern end. Finally, if you're crossing into Canada at the end, ensure your passport is ready before you hit the toll booths at the International Bridge; there's no easy place to turn around once you're in the queue.