Washington ? Traffic deaths have plummeted across the United States to levels not seen in more than a half-century, spurred by technology, safety-conscious drivers and tougher enforcement of drunken driving laws.

The Transportation Department said Thursday that traffic deaths fell 9.7 percent in 2009 to 33,808, the lowest number since 1950. In 2008, an estimated 37,423 people died on the highways.

Government and auto safety experts attributed the improvement to more people buckling up, side air bags and anti-rollover technology in more vehicles and a focus in many states on curbing drinking and driving. Economic conditions were also a factor.

Transportation Secretary Ray LaHood called the new data “a landmark achievement for public health and safety” but cautioned that too many people are killed on the road each year. “While we’ve come a long way,” he said, “we have a long distance yet to travel.”

Forty-one states, the District of Columbia and Puerto Rico saw reductions in highway fatalities, led by Florida with 422 fewer deaths and Texas, down 405.

The rate of deaths per 100 million miles traveled also dropped to a record low. It fell to 1.13 deaths per 100 million miles in 2009, compared with 1.26 the year before.

Last year’s reduction in fatalities came even as the estimated number of miles traveled by motorists in 2009 increased 0.2 percent over 2008 levels.