More people than ever are turning their cars into personal phone booths, with a (m) million and a-half drivers gabbing on cell phones at any given time.
Women and young people are the most common users.
The government says about ten percent of the people on the road during the day are using cell phones. That's up from eight percent in 2004.
Six percent of drivers were holding the phones to their ears, up from five percent last year.
The National Highway Traffic Safety Administration, which issued the report, recommends that motorists use cell phones while driving only during an emergency.
The new data could add fuel to the debate over whether drivers should be limited in their use of cell phones on the nation's highways.