But Fred McLuckie, legislative director at the International Brotherhood of Teamsters, said it's not clear speed limit increases played a role in rising deaths.
Truck driving is "one of the most dangerous jobs in the country," he said. "These guys work long hours. There's a lot of stress. There's greater congestion on our highways. There are dozens of reasons why those numbers could be up."
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.
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