Deaths behind the wheel of an automobile fell last year to the lowest level since the Truman administration, but there was an increase in fatalities among bicyclists, pedestrians, motorcycle riders and big-rig truck drivers, according to federal figures released Monday.

Overall, highway deaths dropped to 32,367, almost two percent lower than they were in 2010, and a 26 percent decline since a peak in 2005. Maryland outpaced the nation with a 2.2 percent decrease, but deaths rose by 3.2 percent in Virginia and 13 percent in the District.

The downward national trend began before the recession took some drivers off the roads, and it accelerated last year. It has been attributed to several factors, including increased use of air bags, seat belts and other vehicle safety features, improved roadway designs, and increasing awareness of the perils of driving drunk.

“In the past several decades, we’ve seen remarkable improvements in both the way motorists behave on our roadways and in the safety of the vehicles they drive,” said David L. Strickland, administrator of the National Highway Traffic Safety Administration.

He said police enforcement of seat belt and sobriety laws have played a key role.

But there already have been indications that the downward trend has ended. Preliminary data for this year indicated that fatalities increased 13.4 percent in the first three months of this year, and the total for April, May and June was 5.3 percent higher than in 2011.

“As we look to the future, it will be more important than ever to build on this progress by continuing to tackle head-on issues like seat belt use, drunk driving, and driver distraction,” said Transportation Secretary Ray LaHood, who has made distracted driving the cornerstone of his safety agenda.

The NHTSA data said the number of people killed in distraction-related accidents increased almost 2 percent, to 3,331, from 2010 to 2011. Federal and highway safety advocates said the increase may reflect better reporting of the distraction issue than an actual increase in fatalities.

The number of people injured in distraction-linked crashes declined by 7 percent, to 387,000 people in 2011, the federal agency said.

The evolution in travel patterns, relaxed safety standards and an improving economy were singled out for three of the areas in which fatalities bucked the downward trend.

The number of bicyclists killed increased by 8.7 percent and pedestrian deaths were up 3 percent.

“Our culture is beginning to move away from driving and toward healthier and greener modes of transportations,” said Jonathan Adkins, deputy executive director of the Governors Highway Safety Association. “We need to be able to accommodate all these forms of transportation safely.”

Adkins said a more-than-2-percent increase in motorcycle deaths was attributed to the fact that “state legislatures continue to listen to anti-helmet rider groups and ignore clear research supporting helmet use and laws.”

The largest increase was a 20 percent jump in the number of drivers and passengers of large trucks killed in accidents.

“There are more questions than answers about what is occurring here,” Adkins said, “but this could be in part to a strengthening economy.”

 The data, collected under a federal system called the Fatality Analysis Reporting System (FARS), indicated that there were 1.1 deaths per 100 million vehicle miles traveled in 2011, down from 1.11 deaths per 100 million vehicle miles traveled in 2010.

The FARS statistics are based on numbers collected by each state, and Adkins cautioned that preliminary data indicates that the decline in highway deaths may end this year.

“Based on what we are hearing from states, we fully expect an increase in fatalities for 2012,” he said.

In 2011, 36 states had fewer traffic fatalities, led by Connecticut (100 fewer fatalities), North Carolina (93 fewer), Tennessee (86 fewer), Ohio (64 fewer) and Michigan (53 fewer). In Maryland, there were 11 fewer deaths than the 496 the previous year, while Virginia saw 24 more people die in 2011 than the 740 who died in 2010, and deaths in the District increased by three to 27.