Millions of Americans will be driving for Independence Day. Police will be watching for drunk drivers.

Holiday travel, combined with holiday drinking, results in hundreds of deaths and injuries every Fourth of July weekend.

Over the four-day-long weekend alone, the National Safety Council estimates that nearly 600 deaths and 66,900 injuries requiring medical attention may occur because of crashes. Experts and law enforcement officials say drunk drivers may be a big contributor.

That's why law enforcement officials are particularly adamant to get the message out to drivers to stay sober, whether driving to a local cookout or going on a road trip to celebrate Independence Day.

'Traffic crashes and deaths are prevented when drivers and passengers simply follow the rules of the road,” Virginia State Superintendent Col. W. Steven Flaherty said in a statement. 'This includes never driving impaired, avoiding distractions while driving and always wearing a seat belt.”

More than 37.5 million Americans are expected to take a road trip this weekend, in one of the busiest travel events of the season. The holiday marks the beginning of summer travel, casual gatherings, outdoor entertaining - and an increase in drunken driving.

On average, about one-third of all road deaths involve at least one impaired driver, data suggests. On holidays, that share tends to be higher. The number rises to 40 percent over the Fourth of July holiday.