In 2012, the number of motorcycles registered in the U.S. was around 9 million. The Department of Motor Vehicles considers a motorcycle to be any two- or three-wheel powered vehicle for on-road, off-road or dual-purpose use.
The majority of all motorcycles driven in the US must be registered in order for them to be used on public highways. This makes it easier to keep track of the number in use. Registrations continue to rise each year with a 75 percent increase in registrations from 1997 to 2007. According to the Department of Transportation, 92 percent of motorcycle owners were male, though female ownership continues to grow.