The rise of micro-mobility has sparked a philosophical discussion on the use of space in America’s dense cities. The more congested a place becomes, the slower and more expensive it is to drive and park standard 4-wheel motor vehicles. Micro-mobility options like bikes, scooters, skateboards, and segways are nimbler because they zip through tight spaces and are easier to store. When part of a “sharing economy” model they’re even better, since people aren’t forced to lug these items around. That’s why, as U.S. cities repopulate, shared micro-mobility has become a nascent industry.

Mopeds could soon join the trend. Wikipedia defines them as “a type of small motorcycle with bicycle pedals…Mopeds typically travel only a bit faster than bicycles on public roads, and possess both a motorcycle engine and pedals for propulsion.” Companies like Vespa have popularized mopeds in the U.S., and several others are trying to make them a sharing economy option.

But globally, mopeds are nothing new. They’re common in Asia, Latin America, and elsewhere as a market response to urban density. Because space is constrained and incomes are limited compared to America, people use smaller vehicles. In Hanoi, Vietnam, for example, mopeds appear by the thousands on thoroughfares and are a prime way of delivering goods.

Moped usage in America is less advanced because we have a different history. Our sprawling cities largely grew around the automobile, and our transportation policy—with its myriad of regulations, subsidies, and eminent domain carveouts—favors car usage. But mopeds are seeing industry growth. According to a report by P&S Intelligence, the market for electric scooters and motorcycles (which in this case roughly fit the Wikipedia definition for mopeds) has expanded, and by 2024 is expected to grow by 28% to $676 million. Introducing a sharing economy component could speed that growth even further.

Revel is the most prominent company so far to try, launching a pilot in New York City, Austin and Washington, DC. Described as the “Uber for electric mopeds,” its mopeds cost $1 to unlock and $0.25 per minute to ride. Riders are responsible for wearing a helmet, and parking in legal on-street spots. The blue-and-black fleet is electric, and about 1,000 are scattered around Brooklyn and Queens.

Scoot is a company doing the same in San Francisco, with hundreds of red-and-black mopeds placed in central neighborhoods. They have a similar price structure, but get cheaper the more one rides, meaning an hour with a scooter costs $10. Muving is a Spanish moped-share company that extended to Atlanta. Scoobi is deploying their fleet in Pittsburgh.

These companies aside, U.S. cities may be a long way from making mopeds a prime transport mode. But there are at least ways cities can encourage them. One would be to recognize the environmental and quality-of-life benefits of moped sharing, and delineate space accordingly. This would mean designating some on-street parking for sheltered bike, scooter and moped storage, rather than using it exclusively for cars. This would help with some of the parking dramas (and tickets) that moped riders already experience.

But the most effective welcome mat would be liberalizing the market. City governments have cracked down on—or in some cases outlaw—bike and scooter share services. Moped share is being primed for similar treatment. Revel had to endure a 4-month pilot in DC, and 9 months in New York City. Even now, usage of the latter fleet is heavily confined to just 20 neighborhoods within two boroughs.

Meanwhile, around the world, mopeds are experiencing major crackdowns. Big Chinese cities have passed restrictions or outright bans against mopeds and other motorcycle genres. The aforementioned Hanoi wants to phase them out by 2030. The concerns are usually some combination of noise, pollution, safety, or the fact that they give these cities a low-class reputation. To that point, Forbes contributor Wade Shepherd writes that in this region (China), it’s the “middle- and lower-income classes that have mostly benefited from the rapid proliferation of this form of personal transport.”

But bringing mobility to the masses is only one reason mopeds are good for cities. They’re also more environmentally-friendly, space-efficient, and easier to get around in than large automobiles. If America wants to be serious about encouraging transportation alternatives, mopeds should be in the mix.