The NHTSA says its researchers observed cell phone use before and after the programs. In Syracuse, hand-held cell phone use and texting dropped by one-third. In Hartford, where the NHTSA says use was far more rampant, hand-held cell phone use declined by 57 percent and texting dropped by nearly three-quarters, the administration says.

"These findings show that strong laws, combined with highly visible police enforcement, can significantly reduce dangerous texting and cell phone use behind the wheel," says U.S. Transportation Secretary Ray LaHood in a statement. "Based on these results, it is crystal clear that those who try to minimize this dangerous behavior are making a serious error in judgment, especially when half a million people are injured and thousands more are killed [each year] in distracted-driving accidents."

The NHTSA says nearly 5,500 people died and 500,000 were injured in 2009 from crashes involving a distracted driver.

Recently the Governors Highway Safety Association (GHSA), which represents the highway-safety offices of states, territories, the District of Columbia and Puerto Rico, says it looked at 350 papers on distracted driving published from 2000 to 2011 to come up with a report that advises states that do not have handheld bans to wait until more research is done before passing laws.

However, the GHSA urges states with laws to enforce them in order to accumulate data. The association is also in favor of bans on hand-held cell phone use by novice drivers.

There is no evidence to indicate whether cell phone or texting bans have reduced automobile crashes, the GHSA says.

Nine states and the District of Columbia have banned all hand-held cell phone use while driving. The district and 34 states have passed laws prohibiting texting while behind the wheel.