The National Highway Traffic Safety Administration's early estimate of 2011 traffic fatalities said there were 32,310 deaths in motor vehicle crashes last year, a drop of 1.7 percent from the previous year.
Safety experts credit more people wearing seatbelts, safer cars and efforts to keep drunk drivers off the road. But they say people are also driving less due to a weak economy.
In the past, when "the economy bounces back and people are doing more discretionary driving and things like that," highway deaths have gone back up, said Jackie Gillan, president of Advocates for Highway and Auto Safety.
NHTSA divides states into 10 regions for its report. Overall, traffic fatalities in the U.S. were down last year, but the three-state Region 9 - California, Arizona and Hawaii - experienced a 3.3 percent increase in fatalities.
The Associated Press contributed to this report.