The highest speed limit in the US is 85 mph (about 137 km/h), and it applies on a 41-mile stretch of State Highway 130 in Texas. No interstate goes that high: the top interstate limit is 80 mph, which eight other states also reach somewhere on their road network. Texas approved the 85 mph limit in 2012, and it is still listed by the Insurance Institute for Highway Safety (IIHS) in November 2026.
| State | Highest limit | Where it applies |
|---|---|---|
| Texas | 85 mph | 41-mile stretch of State Highway 130 |
| Texas | 80 mph | Sections of I-10 and I-20 in West Texas and Highway 45 in Travis County, for passenger cars and light trucks |
| Idaho | 80 mph | Specified segments |
| Montana | 80 mph | Rural interstates; 70 mph for trucks |
| Nevada | 80 mph | Rural interstates |
| North Dakota | 80 mph | Rural interstates, with some sections lower |
| Oklahoma | 80 mph | Portions of the turnpike |
| South Dakota | 80 mph | Rural and urban interstates, unless set lower |
| Utah | 80 mph | Specified freeway or limited-access segments |
| Wyoming | 80 mph | Specified segments |
What is the highest speed limit in the US?
The highest speed limit in the US is 85 mph on Texas State Highway 130, usually shortened to SH 130. IIHS describes it as a 41-mile stretch, and the Texas Tribune reported it as roughly 40 miles when the limit was approved. The road covers Segments 5 and 6 of SH 130.
KSAT reported that those sections run from Interstate 10 in Seguin north to Mustang Ridge, where they connect with the part of SH 130 that was already open and reaches I-35 near Georgetown. So if you drive between San Antonio and the Austin area, this is the road you may meet.
Can you drive 85 mph on all of State Highway 130?
No, the 85 mph limit covers only the 41-mile stretch, not the whole highway. The older northern part of SH 130 toward I-35 is outside that section, so watch for the sign when the road changes and follow whatever number it shows.
Is State Highway 130 a toll road?
Yes, IIHS describes SH 130 as having toll portions, and the 85 mph section was built as a toll road. When the limit was approved, the Texas Tribune reported that a private group was building and operating the road under a concession, with the Texas Department of Transportation (TxDOT) keeping ownership. It is worth checking your toll options before you set out.
How fast is 85 mph in km/h?
85 mph is about 137 km/h. If you are visiting from a country that uses kilometers, 80 mph is about 129 km/h and 75 mph is about 121 km/h. US speed limit signs are in mph, so go by the sign.
Why does Texas allow an 85 mph speed limit?
Texas allows 85 mph because its Transportation Code lets the Texas Transportation Commission set a limit that high on part of the state highway system. The Legislature authorized such limits in 2011, and the commission approved 85 mph for SH 130 in 2012.
The law sets two conditions:
- The road must be designed to accommodate travel at that speed or a higher one.
- The commission must find, after an engineering and traffic investigation, that the limit is reasonable and safe.
Those conditions are why 85 mph remains so rare. Everywhere else, the general Texas figure on the IIHS table is 75 mph, on interstates and other roads alike.
At the time, no US road had a posted limit above 80 mph, so the decision drew attention. TxDOT's spokesman told the Texas Tribune that safety was the top priority and that tests had shown the speed to be safe, while an insurance industry group had warned that higher-speed roads would mean more crashes and claims.
Which states have an 80 mph speed limit?
Eight states have 80 mph as their highest limit: Idaho, Montana, Nevada, North Dakota, Oklahoma, South Dakota, Utah and Wyoming. Texas also has 80 mph on some roads, on top of its 85 mph highway. How widely the limit applies varies a lot from one state to the next.
- Rural interstates generally: Montana, Nevada, North Dakota and South Dakota.
- Specified segments: Idaho, Utah and Wyoming, where the higher limit rests on an engineering and traffic investigation.
- Turnpikes: Oklahoma may post 80 mph on portions of the turnpike if the Oklahoma Turnpike Authority approves.
North Dakota is the latest addition. House Bill 1298, signed on May 5, 2025, set the new limit from August 1, 2025. In Montana, lawmakers raised the limit to 80 mph in 2015, with a smaller rise for semi-trucks. For the full picture, see our table of interstate speed limits by state.
What is the highest speed limit on an interstate?
The highest speed limit on an interstate is 80 mph, because the 85 mph road in Texas is a state highway. South Dakota is the only state whose general figure is 80 mph on both rural and urban interstates, and Idaho and Wyoming list 80 mph on specified urban segments too.
In Texas, the 80 mph limit is written into law for a specific list. It covers parts of I-10 and I-20 in Crockett, Culberson, Hudspeth, Jeff Davis, Kerr, Kimble, Pecos, Reeves, Sutton and Ward counties, and only if the commission finds it reasonable and safe for that section. IIHS adds that sections of Highway 45 in Travis County also carry 80 mph, and that these 80 mph limits apply to passenger cars and light trucks.
Does the 80 mph limit apply to trucks?
Not everywhere. Montana lists 80 mph for cars and 70 mph for trucks on rural interstates, and in Texas the 80 mph sections are for passenger cars and light trucks. If you are driving a truck or towing, look for the separate truck sign.
What is the highest speed limit in the eastern US?
The highest speed limit east of the Mississippi River is 75 mph, found in Maine and on specified segments in Michigan. Maine lists 75 mph on rural and urban interstates as well as other limited-access roads. Every other state in the region tops out at 70 mph or 65 mph.
That gap shows how large the country is, and how different its roads are. Maximum limits by state fall into clear groups: IIHS says 21 states have maximum limits of 70 mph and 11 states have maximum limits of 75 mph on some portion of their roads.
Which state has the lowest top speed limit?
Hawaii has the lowest top speed limit of any state, at 60 mph on its interstates. Its other limited-access roads top out at 55 mph and its other roads at 45 mph. Washington, DC, is not a state, but its maximum is 55 mph on urban interstates and 25 mph on other roads.
Does any US road have no speed limit?
No, every state now has a maximum posted limit, and the IIHS table lists a number for each one. Montana is the famous exception from the past. After Congress repealed the national limit in 1995, Montana had no numeric daytime limit on many roads, only a "reasonable and prudent" standard.
That did not last. Montana Public Radio reports that the Montana Supreme Court ruled in 1998 that the standard was unreasonably vague, and in 1999 the legislature set a daytime limit of 75 mph. So the idea of an American road with no number at all belongs to history.
Is it safe to drive at 85 mph?
It is legal only where 85 mph is posted, and even there the risks rise with speed. IIHS says speed increases the distance you travel before you react, increases the distance needed to stop, makes it more likely that a sudden steering move ends in a loss of control, and raises crash energy out of proportion.
Here is what the research shows:
- When impact speed rises from 40 mph to 60 mph, a 50% increase, the energy to be managed goes up by 125%.
- From 1993 to 2017, each 5 mph increase in a state's maximum limit was associated with an 8% higher fatality rate on interstates and freeways.
- IIHS estimated about 37,000 more traffic deaths in those years than if the 1993 maximum limits had stayed in place.
- In 2024, speed-related crashes accounted for 11,288 deaths, or 29% of all motor vehicle fatalities.
North Dakota's first year at 80 mph is a smaller, local example. The Highway Patrol counted 505 crashes in the new 80 mph areas, up from 469 the year before, although the patrol said one year of data makes it difficult to draw conclusions. A posted maximum is a ceiling for good conditions. Wind, rain, darkness or a full lane of traffic all call for a lower speed.
What does the highest speed limit mean for your next drive?
If your next trip takes you onto SH 130 or across the 80 mph West, you can treat the number as a limit and not a target. Choose the speed that suits your car, your load, the weather and how you feel, and you will reach the end of a long straight road a lot fresher. Watch for lower limits near towns and work zones too, since these fast sections can end quickly. For the latest on the rules for each state, our United States guide is a good place to start.
Ghost is the calm companion for days like that. It runs in the background next to any navigation app and warns you about known fixed speed cameras and average-speed zones about 700 meters ahead, roughly 0.4 mile, and again at 250 meters, with one tone and no voice. It works on CarPlay, Android Auto and Apple Watch and covers more than 125,000 speed cameras worldwide, so even on a road you have never driven, you stay informed, unhurried and on course to arrive safely.
