Washington (CNN) -- Despite efforts to build cars to better withstand accidents and reduce threats posed by distracted driving, traffic fatalities for the first three months of 2012 have shown a "significant increase" compared with government statistics from a year earlier.
An estimated 7,630 people died in motor vehicle traffic crashes for the first quarter this year, a 13.5% increase compared with the same period in 2011, when there were 6,720 fatalities, according to the National Highway Traffic Safety Administration.
An NHTSA spokesman said, "It's too soon to speculate on the contributing factors or potential implications of any increase in deaths on our roadways." The increase follows a downward trend for the past several years.
Transportation safety officials point out the crash fatality rate for the first quarter each year is traditionally significantly lower than the rates for the other three quarters, in part because of the effects of winter weather. However, the winter of 2012 was unseasonably warm and people tend to drive more when the weather is better.
"While it is likely not the only factor involved, AAA agrees that warmer-than-average winter weather may have contributed to higher vehicle miles traveled, and ultimately more fatal crashes," said Jacob Nelson, director of traffic safety advocacy and research with the Automobile Association of America. "These data show there is more work to be done to improve driver safety such as limiting distractions, reducing impaired driving and promoting a culture of safety among motorists."
Data provided by the NHTSA indicates that if the current estimates hold, the first quarter numbers would represent the second largest year-to-year quarterly increase in traffic fatalities since the government began recording them in 1975.
Traffic fatalities in the United States peaked in 1972, with 54,589 killed, according to the Department of Transportation. But since then, there has been stricter enforcement of driving laws and programs to change driving behavior that have helped improve roadway safety.
Preliminary data reported by the Federal Highway Administration shows vehicle miles traveled in the first three months of 2012 increased by about 9.7 billion miles, 1.4% more than 2011.
"After reaching a 60-year low last year, it is disappointing for AAA to see driver fatalities rise," Nelson said in a written statement. "Examination of federal data show that traffic crashes occur more frequently as the number of miles traveled increases."
First-quarter fatalities had been falling since 2006, when there were 9,558 in January through March.
The data on crash fatalities is compiled with information from police accident reports and other sources.
The NHTSA statistical summary can be found at http://www-nrd.nhtsa.dot.gov/Pubs/811642.pdf