Drunken-driving deaths fell in 32 states in 2007, the government reported Thursday, but alcohol-related fatalities increased among motorcycle riders in half the states.

Nearly 13,000 people were killed in crashes in which the driver had a blood alcohol concentration of 0.08, the legal limit in the United States, or at higher levels.

Overall, alcohol deaths were down nearly 4 percent compared with 2006, when nearly 13,500 people died on the highway.

Transportation Secretary Mary Peters said she was disappointed by the increase in deaths involving drunk motorcycle riders. A total of 1,621 motorcyclists were killed in alcohol-impaired crashes in 2007, an increase of 7.5 percent.

Motorcycle riders have been featured in the government's $13 million advertising campaign surrounding the Labor Day holiday. Law enforcement agencies are increasing their enforcement against drunken driving during the end of the summer.

Dean Thompson, a spokesman for the Motorcycle Safety Foundation, said riders who conduct training courses always stress the dangers involved in drinking alcohol before riding.

"The skill set you need in terms of the coordination and balance and things like that, you cannot choose to drink and ride. It's just the wrong choice to make," he said.

Among the states, California had 117 fewer alcohol-impaired driving deaths last year, the largest decrease in the nation. Texas had 108 fewer deaths and Arizona's fatalities dropped by 63 deaths.

California conducted more than 1,000 sobriety checkpoints during the year and encouraged motorists to dial 911 on their cell phones if they spot a potentially drunken driver, said Christopher Murphy, who leads the state's traffic safety office.

"Our vision is really toward zero deaths — everyone counts, so we're not exactly celebrating these numbers," said Murphy, who leads the Governors Highway Safety Association.

North Carolina had 66 more deaths, the most among states, followed by South Carolina with 44 fatalities.

In addition to North Carolina and South Carolina, alcohol-impaired deaths increased in Alabama, Alaska, Delaware, Maine, Massachusetts, Minnesota, Montana, Nebraska, North Dakota, Ohio, Oklahoma, Oregon, Pennsylvania, Virginia, West Virginia, Wisconsin and the District of Columbia.

The latest data followed calls from dozens of college presidents to consider lowering the drinking age from 21 to 18, arguing that the laws lead to binge drinking on campus.

Mark Rosenker, acting chairman of the National Transportation Safety Board, said Thursday he opposed the administrators' effort.

"Age 21 drinking laws have been proven time and again effective in preventing deaths and injuries," Rosenker said. "Repealing them is a terrible idea."