Chances are good you'll be spending some time in the car over this Fourth of July weekend. If the trip will be longer than a couple of hours, you'll need to be prepared. Try these four tips:

1. Bring food.

The key to kids' happiness (OK, the key to my kids' happiness) is snacks in the car. I try to stick with healthy stuff that doesn't make a mess. That means grapes (both fresh and frozen, which helps keep the cooler cool), bananas (make sure to toss those peels into the next available garbage can--never make the mistake of leaving them in a hot car) and easy-to-peel clementine oranges.

2. Bring water.

I know kids like fruit juice and soda, but your car seats don't. Stick with water. It doesn't stain or get sticky when it's spilled. And you can restock for free at the next water fountain. Besides all of that, water is just better for everyone.

3. Get some exercise.

Our rule was no more than two hours in the car at a time, especially when the kids were toddlers strapped into car seats. They need to move. We're big believers in taking country roads, so it was never tough to find a town park to let them run around. If you're a highway lover, pull off at the rest stop. It might not have a swing set, but it will have a patch of grass for running. When it rains, we look for a fast food joint with an indoor play space. It's well worth the price of a cup of coffee or an order of fries.

If you can't get out of the car, you can exercise in the car. My favorite: a variation on the head, shoulders, knees and toes song you can read about here.

4. Read a map.

I know you've got a GPS, but it won't help you find the detours along the way. For that, you need a map. If I hadn't been looking at a map on a recent drive home from Orlando, we never would have known we were just 30 miles from Planes, Georgia, and an improptu visit to the home of former President Jimmy Carter. He was even in town and, had we been able to stick around until Sunday, we could have listened to him teach Sunday School. Or so we were told.

For younger children, print a map of your route off of Mapquest before you go and paste on photos of the things you'll see along the way. When kids get slightly older, let them follow the route on a real map. Once they're ready, give them the responsibility to plot out alternative routes for short distances.

Cindy Richards is the Chicago Parent travel writer and editor of TravelingMom.com.