Only one state, Montana, is left unspoiled with no daytime speed limit. At night, speeds are restricted to 65 mph on interstate highways and 55 mph on two-lanes.

As of 2026, there are no public roads in the United States without a speed limit. While Montana famously had a "reasonable and prudent" daytime speed limit in the late 1990s, the U.S. Supreme Court eventually ruled it unconstitutionally vague, leading the state to implement numerical limits. Today, the highest speed limits in the country are found in Texas, specifically on State Highway 130 (the Pickens Parkway), where the limit is 85 mph. Several other states, including South Dakota, Wyoming, and Montana, have 80 mph limits on certain rural interstates. For those seeking the "no limit" experience, the only legal options are private race tracks or designated land-speed racing venues like the Bonneville Salt Flats in Utah during sanctioned events. In all other jurisdictions, exceeding the posted limit—no matter how desolate the road—can result in significant fines or reckless driving charges.