The campaign against distracted driving has provided another illustration that American drivers are more likely to respond to safety initiatives when they carry the threat of punishment.

A crackdown built around the heavily trumpeted slogan “Phone in One Hand, Ticket in the Other” led to more than 19,000 tickets in Connecticut and New York, resulting in sharp declines in cellphone use behind the wheel, federal researchers found.

The federally funded pilot programs in Hartford and Syracuse were modeled after successful efforts to encourage seat-belt use and discourage drunken driving. Publicity efforts alone, such as the “Buckle Up for Safety” campaign, were high-profile failures, but the “Click It or Ticket” effort that followed is credited with increasing seat-belt use. The weeping victims of drunken driving who appeared in public presentations and in the media captured widespread attention, but experts say sobriety checkpoints provided stronger motivation for the use of designated drivers.

After a two-year assault on distracted driving, Transportation Secretary Ray LaHood provided $400,000 to fund the two programs to test whether coupling a strong public relations campaign with strict enforcement would get drivers to put down their cellphones.

“These findings show that strong laws, combined with highly visible police enforcement, can significantly reduce dangerous texting and cellphone use behind the wheel,” LaHood said. “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 in distracted-driving accidents.”

In Syracuse, police issued 9,587 citations to drivers talking or texting on cellphones during four enforcement periods in the past year. During the same period, police in Hartford handed out 9,658 tickets for illegal phone use.

As the crackdowns were underway, observers from the National Highway Traffic Safety Administration monitored cellphone use and conducted surveys to determine whether an accompanying advertising campaign had made drivers more aware of state laws restricting cellphone use and texting.

The observers concluded that in Syracuse, both hand-held cellphone use and texting behind the wheel declined by one-third. Hartford had a 57 percent drop in hand-held phone use, and texting behind the wheel dropped by nearly three-quarters, they said.

“The success of these pilot programs clearly shows that combining strong laws with strong enforcement can bring about a sea change in public attitudes and behavior,” said NHTSA Administrator David L. Strickland.

In 2009, nearly 5,500 fatalities and 500,000 injuries resulted from crashes involving a distracted driver, according to the NHTSA. Overall, distraction-related fatalities represented 16 percent of total traffic fatalities in 2009.

Nationwide, 34 states, including Maryland and Virginia, as well as the District, have enacted texting bans. Nine states, the District and the Virgin Islands have prohibited all hand-held cellphone use while driving.