The Transportation Department said today 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.

Maine, however, saw highway fatalities increase from 154 in 2008 to 159 in 2009.

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.

Year-to-year declines in highway deaths have occurred in previous economic downturns, when fewer people are out on the road. Traffic deaths decreased in the early 1980s and early 1990s when difficult economic conditions led many drivers to cut back on discretionary travel.

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.

LaHood said the weak economy was a contributing factor as many Americans chose not to go out to bars and restaurants after work or on the weekend.

But he said many motorists are more safety conscious behind the wheel. About 85 percent of Americans wear seat belts while benefiting from safety advances found in today’s cars and trucks.

Side air bags that protect the head and midsection are becoming standard equipment on many new vehicles. Electronic stability control, which helps motorists avoid rollover crashes, is more common on new cars and trucks, while some luxury models have lane departure warnings and other safety features.

Dave McCurdy, president and CEO of the Alliance of Automobile Manufacturers, which represents General Motors, Toyota, Ford and others, said the improvements were “the payoff from years of manufacturer-driven safety improvements, like antilock brakes and electronic stability control systems” along with efforts by law enforcement to keep the roads safe.

LaHood, a former Illinois congressman, has also sought to crackdown on distracted driving, urging states to adopt stringent laws against sending text messages from behind the wheel, as well as other distractions.

The annual highway safety report also found:

— Motorcycle fatalities broke a string of 11 years of annual increases, falling by 16 percent, from 5,312 in 2008 to 4,462 in 2009.

— The number of people injured in motor vehicle crashes fell for a 10th consecutive year. An estimated 2.2 million people were injured in 2009, a 5.5 percent decline from 2.3 million in 2008.

— Alcohol-impaired driving deaths declined 7.4 percent in 2009 to 10,839 deaths, compared with 11,711 in 2008. Alcohol-impaired fatalities fell in 33 states and Puerto Rico.