The number of people killed in crashes connected to driver distraction declined last year, but the government said the problem remains an epidemic for American motorists.

The Transportation Department said Monday that 5,474 people were killed in 2009 in crashes reported to have involved distracted driving -- a 6 percent decline from the 5,838 people killed in 2008.

Distraction-related deaths accounted for 16 percent of all traffic fatalities in 2009 -- the same percentage as in 2008.

The latest data came as the overall number of highway deaths dropped last year to its lowest level since 1950.

The main culprit in driver distracted accidents are cell phones and other mobile devices that keep drivers' eyes off the road.

Transportation Secretary Ray Lahood says the number could be just the tip of the iceberg, because many police reports don't document distracted driving.

"Everybody thinks they can use their cell phone and drive and drive safely and you can't," Lahood said.

The government's report issued on Monday revealed 448,000 people were injured in crashes reported to have involved driver distractions in 2009.

Lahood, a former Illinois congressman, has pushed for states to adopt tougher laws on texting and driving. Tuesday, he will kick off a second summit on distracted driving in Washington, D.C.