Speed limits in the United States are set by each state, so they vary more than in most countries. Here's a practical overview — the posted sign always wins.
Limits are set by state and locality and change over time. This is general guidance, not legal advice — always follow posted signs.
Typical limits by road type
- Rural interstates: commonly 65–80 mph (about 105–129 km/h), depending on the state. A few states allow 80–85 mph on certain highways.
- Urban interstates: often 55–70 mph (89–113 km/h).
- US and state highways: frequently 45–65 mph (72–105 km/h).
- City streets: typically 25–45 mph (40–72 km/h).
- School and residential zones: often 15–25 mph (24–40 km/h).
Why it varies so much by state
Each state legislates its own maximums. Wide, open western states tend to allow the highest interstate speeds, while densely populated states keep them lower. Some states also set different limits for trucks.
Speed in mph — converting to km/h
US signs are in miles per hour. If you think in km/h, remember: multiply mph by about 1.61. So 65 mph ≈ 105 km/h, and 70 mph ≈ 113 km/h. Use the speed converter for any value.
Check your true speed
Vehicle speedometers read slightly high by design, so you may be going a touch slower than the dash shows. To see your real speed over the ground, use the free GPS Speedometer — set it to mph, and it works on any phone with nothing to install.
Drive safely and follow the posted limits, which always take priority over any general guide.