Montana Becomes 3rd State to Allow Lane Splitting

Lane Splitting

Lane splitting, also known as lane filtering, where motorcycles share lanes with cars and trucks to reduce traffic congestion, is a widespread practice around the world. In the U.S., only California allowed the practice for many years, though it was not legally sanctioned until 2016. (Two studies in 2014 showed that the practice is safe.) In 2018, Utah became the second state to legally recognize lane splitting. And now Montana has enacted legislation to allow the practice, which goes into effect on October 1, 2021.

The following is a press release issued by the American Motorcyclist Association:

PICKERINGTON, Ohio — Montana has become the third state to recognize lane filtering, with the Gov. Greg Gianforte’s signature on a bill legalizing filtering of motorcycles under certain conditions. “We applaud the efforts of Montana’s motorcycling community and the state’s legislators, and thank Gov. Gianforte for signing this legislation into law,” said Russ Ehnes, chair of the AMA Board of Directors.

AMA Board Chairman Russ Ehnes and Montana lawmakers. (Photo courtesy of the AMA)
AMA Board Chairman Russ Ehnes and Montana lawmakers. (Photo courtesy of the AMA)

S.B. 9 allows the operator of a two-wheeled motorcycle to overtake stopped or slow-moving vehicles at a speed not in excess of 20 mph, to filter between lanes of stopped traffic traveling in the same direction as conditions permit, and specifies reasonable and prudent motorcycle operation while lane filtering.

“With the signing of S.B. 9, Montanans have recognized the benefits of lane splitting, which allows motorcyclists the choice to filter in traffic when it is safe to do so,” said Tiffany Cipoletti, on-highway government relations manager for the American Motorcyclist Association. 

The bill, sponsored by state Sen. Russ Tempel (R-SD14) and state Rep. Barry Usher (R-HD40), was signed by Gov. Gianforte on March 2 at a public signing ceremony in Helena. Ehnes was in attendance. The bill takes effect October 1, 2021.

California (A.B. 51, 2016) and Utah (H.B. 149, 2018) were the first two states to codify and sign lane-splitting or lane-filtering legislation. Efforts to legalize and formally recognize lane filtering/splitting is under consideration in three other states during the 2021 legislative session.

The AMA endorses lane splitting, given the long-term success in California and the University of California-Berkeley research study showing that the practice enhances motorcycle safety. The AMA will assist groups and individuals working to bring legal lane splitting and/or filtering to their state.

“As lane splitting support continues to gain traction across the country, I am eager to help more motorcyclists engage their state legislatures on this issue,” Cipoletti said.

The full AMA position statement on lane splitting can be found at


  1. I wish there was better distinction in the article between lane splitting and lane filtering. The article seems to use both interchangeably and they are clearly not the same thing. But we don’t have either in Washington State…so…that.

    • Lane filtering and lane splitting are the same thing. Since you think they “are clearly not the same thing,” please explain why.

      • As I’ve heard it explained, filtering is navigating between cars at a light in order to get ahead when the signal changes (see the multiple mentions of “stopped”). Splitting is sharing lanes regardless of speed, again as I understand it.

        Whether the terms are agreed upon, there seem to be different approaches to what is allowed. I’ve read and heard that England allows what I’m calling “filtering”, but not what I’m calling “splitting”. Sounds like Montana is allowing what I’m calling “filtering”. I don’t think I’m alone in this distinction. I think Rider might be somewhat lonely in saying there is none, which is a bit surprising.

        • I agree Mike. My understanding has always been that, while related, Lane Splitting and Lane Filtering are still two different actions. Filtering is the action of splitting lanes when approaching a traffic stop, such as a stop sign or more commonly when approaching a red traffic light. One of the main arguments for allowing the practice of filtering isn’t just for the purposes of getting ahead of traffic, but also for safety reasons. The action of lane filtering positions a motorcyclist between cars at the traffic stop, thus providing better protection from possibly being rear-ended, which we all know is a considerable cause of many serious injuries and fatalities among motorcyclists. I believe the Berkley study specifically pointed this out as one of the main positives in allowing lane filtering.


Please enter your comment!
Please enter your name here