The manufacturer has waged a lobbying campaign at statehouses around the country, winning over lawmakers who see the Segway as a remarkable tool to ease congestion and more.
But worries are growing among doctors and others who fear pedestrians will get hurt by the two-wheeled, 69-pound Segways as the machines zip around at up to 12.5 mph.
The scooter was introduced amid great hype by inventor Dean Kamen, who has claimed his machine will transform the way people live and work just as surely as the automobile did when it replaced the horse and buggy.
The quiet, single-person vehicles are battery-powered, with computers and gyroscopes that allow riders to negotiate curbs and ruts. Tests of a heavy-duty version are under way at factories, resorts and among government employees like postal workers and police officers.
Up until recently, all but three states barred motorized vehicles from sidewalks.
Now the path is clearer. Twenty-four states, including Florida, New Jersey, Tennessee, Washington and Wisconsin, have enacted Segway's proposals into law with surprising speed over the past six months. Legislation in four more states is awaiting governors' signatures.
Washington's law allows the Segway to operate on bike paths and sidewalks. Cities can ban their use on streets with speed limits greater than 25 mph and can restrict their speed in some areas.
Matt Dailida, who oversaw Segway LLC's legislative efforts, said the goal was to lay the groundwork for a 21st-century technology by sweeping aside 19th-century laws.
The Segway dazzled lawmakers when it was demonstrated at state capitols, with many seeing the machine as a way to ease traffic, boost tourism and make business more productive.
"It's amazing," said state Rep. Dan Schooff, a Democrat in Wisconsin. "It's a dramatic kind of breakthrough. It extends the pedestrian environment (and provides) more ways for people to get around."
But pedestrian advocates and doctors are warning about collisions and injuries, and fear the machines could be especially dangerous to children and the elderly. The consumer model, projected to cost $3,000, is about three times as fast as a speedy walker and stands about 3 feet high.
"It just baffles me that lawmakers are so quick to embrace this device based on the assurances of paid lobbyists," said Dr. Gary Smith, director of the Center for Injury Research and Policy at Columbus Children's Hospital in Ohio. "The laws of physics are going to apply to this motorized scooter, as much as they do to any other motorized vehicle."
The new laws vary from state to state, but all allow for the Segway to be used on sidewalks, bike paths and many roads. Some require helmets. They effectively eliminate licensing and insurance. In most states, local governments could act separately to force the machines onto the street.
The National Highway Traffic Safety Administration ruled that the Segway is not a vehicle subject to its oversight.
"I'm a registered nurse," said Tennessee state Sen. Rosalind Kurita, a Democrat who voted against the bill. "This is a big, bulky, perhaps clumsy machine. No helmet, no license, no instruction. What about the people that are legitimately walking on the sidewalk? Do we bump them off the sidewalk?"
The make of the machine, officially the Segway Human Transporter, says it is designed to allow a rider to stop quickly and swiftly back up or move to the side to avoid running into something.
"Someone running down the street is probably more dangerous than someone cruising on one of these. You can stop in the same distance. It's much safer than a bike," said Schoof, the Wisconsin lawmaker.
Marya Morris at the American Planning Association said urban planners view the machines with "skepticism but interest." The Segway does not pollute, gets people out of cars, and could boost mass transit, she said.
But she said that there could be collisions with pedestrians or cars, and that the Segway could discourage walking and lead to even more inactivity among Americans.
The legislation moved so quickly it caught many unawares.
"I don't think any kind of opposition had any chance to set up shop," said analyst Melissa Savage at the National Conference of State Legislatures. "I've not seen anything quite like this before."
In Norman, Okla., Regina Osgood uses a Segway every day, delivering the mail along an eight-mile route with the machine, and not her shoulders, carrying the 35-pound mail load as she zips along streets, sidewalks, even lawns.
"I usually use the Segway wherever I walk," said Osgood, who is taking part in a test in six cities for the Postal Service. "I go up as close as I can, jump off the Segway, run up to the house and then jump back on. It's great."