Teenagers text each other everywhere – in school, at home, on the bus, in movies, and especially while driving.

There are plenty of reasons, of course — with the ability to communicate covertly during a social-studies class high up the list.

In a widely publicized incident, a Mercer Island, Washington, man was accused of causing a five-car pileup after he was distracted by a message on his BlackBerry.

Last week, a bill gained final passage, and would make Washington the first state to impose a specific ban on reading or sending text messages while driving, according to the Denver-based National Conference of State Legislatures.

The milestone is not quite as singular as it sounds: Three states — New York, New Jersey and Connecticut — and Washington, D.C., all have de facto bans on "DWT" under broader laws that prohibit drivers from using a cellphone in any fashion, other than talking on it via a hands-free speaker device.

California is imposing a similarly broad ban, effective in July 2008.

Nonetheless, Washington state’s measure, which the governor is expected to sign into law, brings attention to the practice of texting while driving, which many lawmakers say is more dangerous than talking while driving.

In Arizona, a Democratic state representative has proposed a bill to ban DWT.

The representative said the motivation was an incident last summer in Phoenix, when a teenage driver who was reportedly texting slammed into a stalled truck. The driver was OK, but two of his passengers suffered severe brain and spinal injuries.

At least one other state, Connecticut, has a DWT bill under consideration. The state already has a ban on any hand-held cellphone use while driving, but the new measure would impose a $500 fine.

Under the California law, state residents will risk receiving a minimum $20 fine for using a cellphone, unless they have a speakerphone or an in-ear device that keeps both hands free.

Many states have debated broad bans on cellphone use, but have rejected them in favor of bans for young drivers only. At least 13 prohibit teens or any new drivers from using cellphones.

There are no reliable statistics on how many accidents have been caused by people attempting to send or receive text messages while driving. But it is clear that plenty of people do it.

According to a study released in January by Nationwide Mutual Insurance, about 37% of drivers in their late teens or 20s admitted to having sent or read text messages while driving. By comparison, 17% of drivers in their 30s and 40s admitted doing so; 2% of drivers in their 50s and 60s did.