WASHINGTON (AP) -- Police across the United States plan to crack down on late-night motorists who refuse to buckle their seat belts during last two weeks of this month.

The National Highway Traffic Safety Administration said Wednesday that death rates for night time drivers and passengers were three times higher than those during daytime hours, highlighting the need to improve seat belt use at night.

"Cops from coast to coast will be out there doing seat belt checkpoints," said Nicole Nason, administrator of the National Highway Traffic Safety Administration. "They will be making more traffic stops; they will be writing more tickets."

The annual "Click It or Ticket" campaign uses checkpoints, patrols and advertisements to enforce seat belt laws. It runs from May 21 through June 3 and includes the Memorial Day on May 28, when large numbers of Americans drive for near-to-home holidays.

About 80 percent of motorists wear seat belts, but the numbers of those complying with the law drops about 10 percentage points during the night, according to government estimates.

A study released by NHTSA on Wednesday found that of the more than 15,000 motorists who died in 2005 traffic crashes between 6 p.m. and 6 a.m., nearly two-thirds were unbelted.

NHTSA estimates that lap and shoulder safety belts reduce the risk of death for those in the front seats of passenger cars by 45 percent and the risk of moderate-to-critical injuries by 50 percent.

The Bush administration has urged more states to enact laws that allow police to stop motorists solely for failing to wear their seat belts. The laws, called primary enforcement safety belt laws, have been passed in 26 states, the District of Columbia and Puerto Rico, a U.S. territory.

The remaining states have secondary enforcement, which allows tickets for seat belt violations only if motorists are stopped for another offense. New Hampshire has no seat belt law for adults.