In the 1950s and early 1960s, the motorized bicycle - also known as a moped or motor scooter - was a popular mode of transportation among the teen and college-age crowd.

But the small, two-wheel vehicle, which got great gas mileage, just about disappeared after the larger and in-expensive, Japanese motorcycles started to compete with American motorcycle manufacturers in the mid-1960s.

By the early 1980s, foreign and domestic motorcycle manufacturers were again marketing the motor scooters in the United States. Since then, sales have increased as more people use them for short trips to work or school in cities and towns.

But confusion persists as to who legally can operate a motor scooter, and what state licensing and insurance requires. Although motorcycles and motor scooters are similar in many ways, they differ greatly when it comes to operating requirements.

The Missouri Department of Revenue doesn't classify the moped as a "vehicle" or a "motor vehicle," so it cannot be titled or licensed. If they are stolen, it's hard to recover them because there is no computer record of mopeds.

Because of their small engine size and speed limitations, motor scooters are not permitted to operate on interstate highways in Missouri, or where the minimum speed limit is above 30 mph.

Although the operator of a moped must have a valid Missouri driver's license, they don't have to take the motorcycle written examination and skills test.

In addition, a motor scooter operator is not required to wear a helmet or show proof of liability insurance.

In contrast, the operator of a motorcycle with engines larger than 50 cubic centimeters, must have the vehicles titled, inspected, and licensed.

To operate a motorcycle, they must also have a motorcycle-qualified endorsement to their operator's license, show proof of motor vehicle liability insurance on the motorcycle, and they must wear a helmet.

Many law enforcement officers agree that legislation regulating motor scooters allows the motor scooter operator to avoid the more strict requirements for licensing and operating the same type of two or three-wheeled vehicle.

Scott City Police Chief Danny Club said motor scooters and motorcycles both operate on the public streets and highways, and must contend with the same traffic hazards.

"It seems to me the law on motor scooters discriminates against motorcycle owners and operators because they must meet licensing and skills testing requirements that motor scooter operators are not required to meet," Clubb said. "It doesn't matter whether you're on a scooter or a motorcycle, the rules of the road and the traffic hazards are the same."

Patrolman Ken Rinehart of the traffic division of the Cape Girardeau Police Department said there are many young, inexperienced, and unlicensed motor scooter operators in the city.

While checking for licenses, Rinehart discovered the operators were as young as 12 or 13 years old, which, of course, is against the law.

Lt. Richard Knaup of the Jackson Police Department said that although motor scooter operators aren't required to show proof of liability insurance, they are liable for damages is they are at fault in an accident.

"Even though these scooters are small, they can still cause a lot of damage to the newer cars if they hit one," Knaup said.

Chaffee Police Chief Larry Bledsoe said the idea of exempting motor scooter operators from the same licensing and skills testing required for motorcycle operators, "seems kind of stupid.

"Both are the same kind of two-wheel vehicles, and you can get hurt just as easily on a motor scooter," he said. "The motor scooter is even smaller and harder to see on the street than the motorcycle."

Some cities, including Cape Girardeau, prohibit passengers from riding motor scooters not designed to carry passengers. Rinehart said he used to issue a warning to the operator of the motor scooter until an incident that occurred last weekend.

"I was in my patrol car on Broadway at Caruthers last Saturday night, around dusk. A motor scooter with a passenger stopped for the light just ahead of me. The passenger put his feet on the pavement at about the same time the light changed. The operator literally drove out from underneath the passenger, causing him to fall back on the pavement."

The passenger wasn't hurt, and the driver of the car behind the scooter realized what happened and didn't move.

"That's when I decided no more warnings," Rinehart said. "From now on, when we see a motor scooter designed for one person carrying a passenger, the operator will be stopped and cited."

Chaffee Police Chief Jerry Bledsoe said he doesn't see any difference in motor scooters and motorcycles when it comes to wearing a helmet. "The law requires a motorcycle or ATV operator to wear a helmet, why not the same for a motor scooter operator?" Bledsoe said. "Especially when the safety people now recommend that bicycle riders wear helmets."

Illinois has a somewhat different classification for motor scooters, which are defined as a two-wheel vehicle with an engine size of 150 cubic centimeters or less.

Unlike Missouri, however, motor scooters in Illinois must be licensed, and have liability insurance. The operator of a motor scooter must have a Class L operator's license that requires a written examination and motorcycle skills test to demonstrate they know how to operate the vehicle correctly and safely. No helmet is required.

Motor scooters in Illinois also are prohibited from any federal or state highway with a minimum speed limit of 45 mph.