WASHINGTON On the Fourth of July, there will be fireworks. There will be barbecues. And there will be about 44 million Americans traveling to and from these festivities. In order to ensure that all of us return home safely, it's more important than ever that we know our limits.

Thanks to over two decades of "Don't Drive Drunk" campaigns, nearly 170 million Americans who enjoy alcoholic beverages do so responsibly. The legal limit is 0.08 BAC (blood alcohol concentration) in all 50 states. Over the holiday weekend, that means friends and family can feel free to enjoy beer, wine, or spirits and still drive home, as long as they enjoy in moderation.

But safe limits for driving aren't confined to drinks. Many drivers don't realize that it's just as important to remain under the limit of other influences (speed, distractions, and fatigue) when climbing behind the wheel. Since drunk driving is such a widely recognized risk, many researchers use its legal 0.08 threshold as a standard against which other driving behaviors are compared.

TAKE SPEED, for instance.

You probably know that speeding is dangerous. But would you have guessed that speeding just 6 miles per hour (mph) over the limit is as risky as driving with a 0.08 BAC? A group of researchers determined comparable BAC levels for various degrees of speeding and also found that, for example, the danger of driving 13 mph over the limit is akin to having a BAC of 0.21 percent -- the equivalent of almost eight drinks in one hour for the average man.

With speed ranking as the No. 1 cause of fatalities and collisions on U.S. highways, its limit is a crucial one.

Unlike speed, there are few legal restrictions on a different threat: distracted driving. Whether it's putting on makeup, chatting on the phone, or one of countless other distractions, these behaviors impact a driver's reaction time in a manner much like drunk driving. Researchers at the University of Utah discovered that mobile phones impair drivers even more than a 0.08 BAC.

Though most of us would never drive drunk, we don't think twice about multitasking behind the wheel. More than 80 percent of drivers admit to blatantly hazardous behavior while navigating traffic, such as changing clothes, painting fingernails, and even shaving. Experts estimate that 1 million people each day chat on their mobile phone or send text messages while driving. And for dangerous activities like that, there's no safe limit.

HOW MANY times have you climbed behind the wheel when you'd rather be climbing in bed?

The National Sleep Foundation reports that "drowsy driving is as dangerous as drunk driving." But even though sleep deprivation impairs a driver as much as a 0.08 BAC, three out of every five adult drivers have driven while drowsy, according to a 2005 poll. More than a third reported actually falling asleep at the wheel.

In addition to getting eight hours of shut-eye, you'll want to remember a few other "limits" for safe driving this Independence Day.

Psychology researchers warn against DWA (driving while angry). "Emotionally impaired driving" significantly impacts perception and judgment. In fact, "high-anger" drivers are three to four times more likely to engage in aggressive driving behavior than level-headed folks. And reckless driving heightens the likelihood of causing a wreck.

Millions of drivers have heard the dangers of driving drunk. And now, safety officials must also educate the public of the importance of other "limits" for the roadway. Anger, sleep, distraction, alcohol, and speed should make up the Fourth's lifesaving checklist.

We'll have to wait for the ads saying "Friends don't let friends drive drowsy" and the public service announcements warning teenagers not to accept a ride from a text-happy friend. So for 2008, just remember: "Know Your Limits."
Sarah Longwell is the managing director of the American Beverage Institute, an association of restaurants committed to the responsible serving of adult beverages. Contact her at (202) 463-7110 or longwell@abionline.org.