Bicyclist deaths jumped 8.7 percent and deaths of occupants of large trucks increased 20 percent, the National Highway Traffic Safety Administration said in an analysis of 2011 traffic deaths.
Overall traffic fatalities dropped 1.9 percent, to 32,367. The decline came as the number of miles driven by motorists dropped by 1.2 percent.
Last year also saw the lowest fatality rate ever recorded, with 1.10 deaths per 100 million vehicle miles traveled in 2011, down from 1.11 deaths per 100 million vehicle miles traveled in 2010.
The increase in bicycle deaths probably reflects more people riding bicycles to work and for pleasure, said Jonathan Adkins, deputy executive director of the Governors Highway Safety Association, which represents state highway safety agencies.
Washington, D.C., for example, reports a 175 percent increase in bicyclists during morning and evening rush hours since 2004. The city also tripled its bike lane network during the same period.
"Our culture is beginning to move away from driving and toward healthier and greener modes of transportations," Adkins said. "We need to be able to accommodate all these forms of transportation safely."
The increase in deaths of large-truck occupants is more puzzling, but may be due to more trucks returning to the road as the economy improves, he said.
"There are more questions than answers about what is occurring here," Adkins said. NHTSA said the agency is working with the Federal Motor Carrier Administration to gather more information to better understand the reason for the increase.
Industry officials suspect there may be a connection between states increasing their speed limits and the increase in deaths, Sean McNally, a spokesman for the American Trucking Associations, said. Texas, for example, recently increased the speed limit 85 mph on Highway 130 between Austin and San Antonio, the fastest in the nation, he noted.
Congress passed a transportation bill earlier this year that directs NHTSA to study how well large trucks protect their occupants in crashes.
Motorcycle deaths also rose 2.1 percent, marking the 13th time in the last 14 years that motorcycle rider deaths have risen.
Despite the overall progress in 2011, preliminary crash data for this year shows that motor vehicle deaths and injuries are trending upward again, Jackie Gillan, president of Advocates for Highway and Auto Safety.
More Nation & World Headlines
McCarthy withdraws candidacy for U.S. House speaker 9:59 a.m. NASA opens up patents to inventors, for free The kids are all right with breaking up in person New push could revive Ex-Im Bank Ben Carson leads Clinton in key states Putin spends birthday playing hockey with NHL stars Russia fires missiles as Syrian troops launch ground push Scientists win Nobel chemistry award for work on DNA repair
Our new comment system is not supported in IE 7. Please upgrade your browser here.