Lane Splitting and Lane Filtering Laws Explained

Three Terms That Get Mixed Up

People use lane splitting, lane filtering, and lane sharing as if they mean the same thing, but they describe different maneuvers, and the law treats them differently. Getting the words right is the first step to getting the law right.

The short version: splitting happens at speed between moving traffic, filtering happens slowly past stopped or crawling traffic, and sharing means two riders using one lane together. Only one of those is broadly legal in a single state, a few are narrowly legal in a handful of states, and the rest are illegal across most of the country.

• Lane splitting: riding between two lanes of traffic that are both moving, usually to get past slower flow
• Lane filtering: moving past stopped or very slow traffic at low speed, typically near a red light or in a jam
• Lane sharing or co-riding: two motorcycles riding side by side within a single lane, which is a courtesy practice, not a way to pass cars

California: The One State That Allows Splitting

California is the only state that broadly permits true lane splitting. Vehicle Code section 21658.1, effective in 2017, expressly allows a motorcycle to ride between rows of moving traffic, and it directs the California Highway Patrol to publish safety guidelines for doing it.

Those guidelines are advice, not a separate offense. They point riders toward splitting only when it is safe, keeping speed close to the flow of traffic rather than blasting past it, and avoiding the practice in rain, glare, or darkness. Ignoring the guidance will not earn you a ticket on its own, but it can weigh against you if you are involved in a crash, so California riders treat the guidance as the practical rulebook.

States That Allow Limited Lane Filtering

A small group of states allow filtering, which is the slow-speed version, but only under tight conditions. These laws are narrow on purpose: they target stalled traffic and red lights, not freeway speeds. The exact numbers differ by state, so a maneuver that is legal in Utah may break the rules in Montana.

As of 2026, the states with filtering laws include Utah, Arizona, Montana, Colorado, and Minnesota. Read the conditions carefully, because the speed caps and the situations they cover are not the same from one to the next.

• Utah: allowed only where the posted limit is 45 mph or less, on a road with at least two lanes in the same direction, between stopped vehicles, and at no more than 15 mph
• Arizona: allowed when traffic is stopped on a road posted at 45 mph or less, and the rider does not exceed 15 mph
• Montana: allowed when lanes are wide enough to pass safely and the other vehicles are stopped or moving no faster than 10 mph, with the motorcycle capped at 20 mph
• Colorado: legal since 2024 when traffic is completely stopped, the rider stays at 15 mph or less, and passes between vehicles going the same direction without using the shoulder
• Minnesota: filtering became legal in 2025 under its own low-speed conditions

Why the Conditions Are So Specific

The narrow speed limits are not red tape. Filtering laws are written around a simple idea: when traffic is stopped or barely moving, a rider passing slowly between lanes has more time to react and far less energy in a crash. Push the speed up and that safety margin vanishes, which is why most filtering caps sit between 10 and 20 mph.

It also explains why these states bar filtering on freeways and high-speed roads. A 45 mph posted limit is roughly the line where lawmakers decided the practice stops being low-risk. When you read your own state's statute, pay attention to three things: the speed cap on the motorcycle, whether the surrounding traffic must be fully stopped or merely slow, and which roads are off limits.

Where It Remains Illegal

In most of the country, both splitting and filtering are illegal. In those states, a motorcycle must stay within a single lane and follow the same lane discipline as any other vehicle, which means waiting in line at a light and not slipping between cars to get ahead.

Crossing a state line does not carry your home rules with you. A rider who filters legally at home can be ticketed for the same move one state over. If you are touring or commuting across borders, check each state's rule rather than assuming the practice travels with you.

How to Do It Safely Where It Is Legal

Where the law allows splitting or filtering, technique matters as much as legality. The goal is to move through a gap, not to live in it. Keep your speed only slightly above the surrounding traffic, stay off the move entirely when the gap is too narrow, and never assume a driver sees you, because many will not be expecting a motorcycle beside their door.

Watch for the warning signs of a closing gap: brake lights, a turn signal, front wheels angling toward your line, or a driver glancing at a mirror. Cover your brakes, keep your eyes well ahead, and be ready to abort back into a single lane. Filtering is safest at a dead stop, such as the front of a red light, where the cars around you cannot suddenly move.

• Keep your speed within the legal cap and close to the flow, not far above it
• Skip any gap that is too tight, and ride a straight, predictable line
• Watch for brake lights, signals, and turning wheels that signal a closing gap
• Wear high-visibility gear and assume drivers have not seen you

Why It Is So Controversial

Lane splitting divides riders, drivers, and lawmakers. Supporters point to research suggesting that a motorcyclist filtering through stopped traffic is less likely to be rear-ended, and that getting bikes out of dense traffic can ease congestion. Critics counter that the practice startles drivers, invites close calls, and is hard to police, which is why most states have been slow to adopt it.

The result is a patchwork that changes often. Several states added filtering only in the last few years, and at least one has its provision set to expire unless lawmakers renew it. That churn is exactly why no single national rule exists, and why a guide like this can only point you toward your state's current statute rather than replace it.

What the Knowledge Test Expects

On the motorcycle written test, you are expected to know your own state's rule, not the national average. A question may ask whether lane splitting is legal where you ride, or under what conditions filtering is allowed, and the correct answer is the one that matches your state's law on the day you test.

Because these laws shift, do not rely on memory or on advice from another state. Confirm the current rule with your state motor vehicle agency or rider handbook before the exam, and again before you put it into practice. Treat any list, including this one, as a starting point that you verify against the official source.