Traffic Laws That Vary Dramatically from State to State

This is one of the most inconsistently regulated areas in U.S. traffic law. Some states ban all handheld use of a phone while driving — meaning you cannot hold a phone to your ear, text, or even briefly check a map without a hands-free setup. Others restrict only texting while allowing handheld calls. A smaller number have more limited restrictions that apply only to certain driver categories, such as novice drivers or those in school zones.

The fine structures also vary widely. Penalties in some states run well over $100 for a first offense, while others treat first offenses more leniently. If you're traveling between states, it's safest to use a hands-free mount or Bluetooth system regardless of local law — the inconsistency itself is a reason not to rely on what you know from home.

In most U.S. states, turning right on a red light is permitted after a complete stop — unless a sign prohibits it. However, New York City is a well-known exception: right turns on red are prohibited throughout the five boroughs unless a sign explicitly allows it. Some other cities and jurisdictions have added similar blanket prohibitions or expanded restricted intersections in recent years, particularly in dense urban areas.

Even where the general rule allows it, individual intersections in any state can post "No Turn on Red" signs based on sight-line issues, pedestrian volume, or traffic flow concerns. Treating every red light as a full stop and checking signage before turning is the habit that protects you everywhere.

The federal 55 mph national maximum speed limit was repealed in 1995, returning full control of speed limits to individual states. Today, rural interstate speed limits range from 65 mph in some states to 85 mph in parts of Texas. Most western states — including Utah, Wyoming, Nevada, and Idaho — post limits of 80 mph or higher on certain rural interstates.

This matters for two reasons. First, the speed you set your cruise control to in one state may put you over the limit the moment you cross into the next. Second, many states also enforce minimum speed limits on interstates, meaning driving significantly below posted traffic flow can also result in a citation. See our guide to speed zone misjudgment for more on how posted limits interact with enforcement.

All 50 states have some version of a "Move Over" law requiring drivers to shift lanes or slow down when passing emergency vehicles stopped on the roadside. However, the specifics vary considerably. Some states extend the law to cover tow trucks, utility vehicles, and highway maintenance workers — not just police and fire vehicles. Others require a lane change only when safely possible, while some mandate a reduction to a specific speed if changing lanes isn't feasible.

Violations carry serious consequences in most states, including fines, license points, and in some cases misdemeanor charges. The law is actively enforced, and roadside stops are inherently dangerous situations — compliance protects workers' lives as much as it protects your driving record.

Radar detectors — devices that alert drivers to the presence of speed-enforcement radar — are legal in private vehicles in most U.S. states. However, Virginia and Washington D.C. prohibit their use entirely, with fines and possible device confiscation on the line. In Illinois, New York, and New Jersey, detectors may be legal in passenger cars but prohibited in commercial vehicles.

Federal law also prohibits radar detectors in any commercial motor vehicle over 10,000 pounds gross vehicle weight, regardless of the state. Drivers who cross state lines with a detector should be aware that what's permitted at home may not be permitted in the next state — and that ignorance of the prohibition is not a recognized defense.

Most states require slower vehicles to keep right on multi-lane roads and reserve the left lane primarily for passing. But how strictly this is enforced — and what exactly the law says — differs. Some states, including Georgia, Indiana, and New Jersey, have relatively strict "keep right" statutes that can result in citations for lingering in the left lane even when traffic is light. Other states treat it more as guidance than an enforceable rule.

Passing on the right is generally permitted on roads with multiple marked lanes going in the same direction, but on two-lane roads, passing on the right is restricted or prohibited in most states. The nuance matters most on two-lane state highways and rural roads where the rules are less intuitive than on a standard interstate. For a broader look at how lane and road rules affect everyday driving, the new driver's guide to American roads is a useful reference.

A number of states require drivers to turn on headlights whenever windshield wipers are in use — not just after dark or in heavy rain. States including Florida, Virginia, and several others have codified this as a formal legal requirement, not just a safety recommendation. The rationale is visibility: headlights make vehicles easier to see for other road users in adverse conditions, even in daytime.

In states without a specific wiper-headlight law, turning lights on in rain is still broadly advisable and may be required if visibility drops below a certain threshold (commonly 500 feet or less). Drivers unfamiliar with the law in a state they're passing through can inadvertently be in violation simply by following what's standard practice back home. See our coverage of nighttime vs. daytime driving differences for more on how visibility conditions change the legal and safety picture.