RALEIGH, N.C. — Starting Dec. 1, texting while driving could cost you.

Gov. Bev Perdue on Friday signed into law a bill that bans drivers from text messaging or sending e-mails with their cell phones.

Thirteen states and the District of Columbia currently prohibit text messaging by drivers, nearly double the number just four months ago, according to the national Governors Highway Safety Association, which represents state highway safety agencies.

Supporters of the legislation say texting drivers often look down to type or keep an unstable hold on the steering wheel while typing with both hands.

Under the law, drivers would have to either pull over or wait until they have stopped their vehicle before they could text or e-mail. Violators could face a $100 fine, plus court costs.

School bus drivers, who are already barred from cell phone use on the road, would now be subject to the texting ban as well.

The bill, which narrowly passed in the Senate last week by a vote of 30-18, makes exceptions for emergency responders, as well as people who use voice-activated technology or access global navigation systems.

Senators complained it was wrong to pass a law that is difficult for police to enforce, but supporters have said there is value in sending a message.

"It's all about safety, and I think we have a lot of law-abiding citizens," said Ron Wyatt, president of a local chapter of the North Carolina Fraternal Order of Police. "If people know it's illegal, we'd hope they'd abide by those rules."

It will still be legal for adult drivers to make calls on a cell phone. A 2006 law already made it illegal for young drivers to use a cell phone, with a few exceptions.