More Americans than ever are using cell phones while driving according to a study by the National Highway Traffic Safety Administration (NHTSA). Driver cell phone use increased in 2005, with 6 percent of drivers on handheld phones in 2005 nationwide compared to 5 percent in 2004.

This result is from the National Occupant Protection Use Survey (NOPUS), which provides the only probability-based observed data on driver cell phone use in the United States. The NOPUS is conducted annually by the National Center for Statistics and Analysis of NHTSA.

The 2005 rate translates into 974,000 vehicles on the road at any given daylight moment being driven by someone on a handheld phone. It also translates into an estimated 10 percent of vehicles in the typical daylight moment whose driver is using some type of phone, whether handheld or handsfree. The 2005 survey also found the following:

- Handheld use increased in a number of driver categories, including female drivers (from 6 percent in 2004 to 8 percent in 2005), drivers age 16-24 (8 percent in 2004 to 10 percent in 2005), and drivers in suburban areas (4 percent in 2004 to 7 percent in 2005).

- The incidence of drivers speaking with headsets on while driving also increased in 2005, from 0.4 percent of drivers in 2004 to 0.7 percent in 2005.

- In the first nationwide probability-based estimate of the incidence of handheld device manipulation, the survey found that 0.2 percent of drivers were dialing phones, checking PDAs, or otherwise manipulating some hand-held device while driving in 2005.