Ever looked at a map of the United States and wondered about that massive vertical vein running from the Great Lakes all the way down to the humid tip of Florida? That is Interstate 75. It's legendary. If you've ever planned a road trip from the Midwest to Disney World, you’ve likely spent some quality time—maybe too much time—on this stretch of asphalt.
But how long is I-75, exactly?
The short answer is 1,786.47 miles. In kilometers, that’s about 2,875.04 km. Honestly, it's a beast. It is currently the second-longest north-south interstate in the country, sitting right behind the infamous I-95. Nationally, it ranks as the seventh-longest interstate overall.
Where does I-75 actually start and end?
Most people assume it just goes "from Michigan to Florida," but the specific points are pretty cool.
On the northern end, it terminates in Sault Ste. Marie, Michigan. Specifically, it ends right at the International Bridge at the Canadian border. You can literally look across the water and see Ontario.
On the southern end, things get a little more "Miami traffic-y." It officially ends at the Hialeah–Miami Lakes border in Florida. It hooks up with the Palmetto Expressway (SR 826) and the Gratigny Parkway (SR 924). If you keep going south, you're basically in the Everglades or heading toward the neon lights of Miami.
The State-by-State Breakdown
I-75 isn't just a long road; it’s a collection of very different vibes. You go from the snow-covered Upper Peninsula to the alligator-filled swamps of Florida. Here is how those 1,786 miles are split up:
- Florida: 470.88 miles. This is actually the longest segment of any interstate in a single state east of the Mississippi River. It’s huge. You’ll hit Tampa, the Gulf Coast, and the famous "Alligator Alley."
- Michigan: 395.54 miles. Often called "Michigan's Main Street." It carries you across the massive Mackinac Bridge, which is an experience in itself.
- Georgia: 355.11 miles. If you’ve ever driven through Atlanta at 5:00 PM, you know these miles feel like they take three days.
- Ohio: 211.30 miles. You’ll pass through Cincinnati, Dayton, and Toledo. It's a heavy industrial and shipping corridor.
- Kentucky: 191.78 miles. Beautiful rolling hills and horse country. It’s a bit of a breather between the chaos of Ohio and Tennessee.
- Tennessee: 161.86 miles. This is the shortest stretch of the route. It’s mountainous, especially around the Jellico area near the Kentucky border. Watch your brakes on those downgrades.
Why I-75 feels longer than it is
If you ask a trucker or a "snowbird" driving a Winnebago, they’ll tell you I-75 feels like 5,000 miles. Why?
Part of it is the sheer volume of traffic. I-75 is a primary artery for logistics. You are constantly surrounded by semi-trucks. Then there are the bottlenecks. Atlanta is the obvious one, but the "Cut-in-the-Hill" in Northern Kentucky near Cincinnati is another legendary spot for brake lights.
Also, the landscape changes are dramatic. You start in the rugged, pine-heavy North, hit the urban sprawl of the Midwest, climb the Appalachian foothills in Tennessee, and eventually hit the flat, palm-tree-lined horizons of the South.
Surprising facts about the route
I-75 wasn't just built overnight. It follows parts of the old Dixie Highway, which was the original way people moved from the North to the South before the Interstate Highway Act of 1956.
Another weird detail: I-75 in Florida has a section called Alligator Alley. For about 80 miles between Naples and Weston, you’re basically cutting through the heart of the Everglades. Back in the day, it was a dangerous two-lane road. Now it's a fenced-off four-lane highway, but you can still spot gators sunning themselves in the canals right next to the shoulder.
In Michigan, I-75 is the only way to reach the Mackinac Bridge. If you want to get to the Upper Peninsula without going through Wisconsin, you’re taking the 75.
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Planning your trip: Actionable tips
If you're actually planning to drive the whole thing, don't try to hero it in one go. 27 to 30 hours of driving is the reality once you factor in gas and food.
1. Timing is everything. Avoid Atlanta between 7:00 AM – 10:00 AM and 3:30 PM – 7:00 PM. If you can, time your drive so you hit Georgia in the middle of the night or on a Sunday morning. Your sanity depends on this.
2. Watch the Jellico Mountain. On the Tennessee/Kentucky border, the elevation changes are steep. In the winter, this is the first place to freeze and get nasty. Check the weather specifically for the "Jellico pass" before you head out.
3. Use the apps. Since I-75 is a construction magnet, use Waze or Google Maps even if you know where you’re going. A single overturned cabbage truck in south Georgia can add three hours to your trip before you even see a sign for it.
4. Fuel up strategically. Gas prices usually drop once you cross the border from Ohio into Kentucky, and Georgia often has cheaper fuel than Florida.
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I-75 is more than just a measurement of miles. It's a massive cross-section of American life. Whether you're hauling freight to Detroit or taking the family to Siesta Key, those 1,786 miles are a rite of passage for anyone living east of the Mississippi.
The next time someone asks how long I-75 is, you can tell them it’s exactly 1,786.47 miles of pure American scenery, orange juice stands, and probably a few construction barrels.