The Booths had made it four hours, all the way from Arlington County to New York, before the whiny question that all parents come to dread drifted forward from their 3-year-old daughter in the back seat: "Are we there yet?"

No, we're not there yet. Not close. Boston is another four hours away.

Unlike generations of family vacationers before her, though, Megan Booth could do something more than try to amuse her daughter, Mikayla, with a song or lame license plate game. She put on a DVD.

"We put the movie in, and she stopped whining," Booth said. "It made the trip way easier."

For as long as Americans have piled the kids into the car and taken vacations, they have shared the bond that comes with the pure tedium of a good, long road trip: The inane games. The fights with siblings. The inevitable discussion about who hit whom first. The excitement-crushing news that Grandma's house is three hours away.

But now, with the proliferation of attention-grabbing DVD players, the great American road trip has forever changed. Just as diapers are packed for baby and towels are packed for the beach, movies are tossed in so bored and fidgety children will have something to do for all those mind-numbing hours on the road. They get to watch Elmo, Shrek and their other favorites, and parents get to drive in peace.

"It's the best investment we have ever made," said Judi Rockhill of Silver Spring. When a normal 21/2-hour ride last Thanksgiving turned into a 51/2-hour nightmare, "we had two Cinderellas and two or three episodes of 'Blue's Clues,' and it was the quietest trip ever, and it was fabulous," she recalled.

DVDs were first offered in cars in the late 1990s, and they're now readily available in hundreds of models.

In most models, the screens flip down from the center of the ceiling directly behind the front seats, though some are fitted into the backs of front seats, like on airplanes. Many parents also use portable DVD players, especially if they have multiple children who don't like to watch the same shows.

Video screens are a primary part of the refashioning of the American car from simple vehicles into traveling homes, with all their comforts and diversions. High-tech audio systems, often with separate speakers for different zones, outlets for carry-on electronics and closet-style cargo space are the features du jour. The Honda Odyssey minivan even can include an "in-floor Lazy Susan."

"Before, the car was seen as a tool, a necessity that you used when you needed to use it," said Brian Moody, road test editor for Edmunds.com. "Now it's still a tool, but it also fulfills recreational things, too."

Even as parents have come to rely on DVDs as their saviors against hours of back-seat whining and fighting, many fret over what is lost each time Elmo appears and the countryside becomes just a faint flicker in the background.

"I don't want them to be little TV heads," said Rockhill, who initially fought the idea of a DVD player. "It makes for a very quiet ride, which is nice, but they also don't see very much because they're just staring at a screen."

Rockhill and other parents said they worry about the lost pleasures of the journey. There's something to be said for all those inane little games. She also doesn't want her children to miss out on those odd bits of roadside Americana that become treasured memories.

"I remember going from Massachusetts to Allentown, and there was a white castle somewhere in New York," Rockhill said. "I always liked that. It was kind of interesting to see. They don't see that stuff."

Rockhill said she misses out, too. She doesn't have that window into her children's minds that she does on local trips, when the DVD player is off-limits. "The Mormon temple, there's a princess that lives in that building, according to my kids," she said. "I like hearing different things in their imagination."

Still, many of today's parents say movies are necessary because they're up against more than their parents faced. For starters, a lot of not-so-long trips stretch on for hours because of traffic jams. Not exactly much to see there. Also, today's parents make more trips because family and friends tend to live farther from each other.

And in days gone by, bored children were free to move around. Remember lying across the back seat? Sitting on the floor? Or climbing over the seat to the one that faced backward, the one in the way, way back?

All those things are off-limits these days. The younger ones are strapped into their special seats, and the older ones are buckled tight for safety.

"My brother and I used to sit on the floor or in the way back of our hatchback and could do more things," Booth said. "I remember we used to play board games and stuff. Kids in car seats really can't do that."

Of course, DVD players don't solve all problems. There may be fewer "are we there yets," but there are whole new choruses of "it's my turn to pick" and "I don't want to watch that."

Some also question how safe it is to have a DVD player in a car. Even though drivers can't see the screens, videos can draw their attention. Safety advocates also said they can create blind spots.

"It really does block the view in many cases," said Judie Stone, president of Advocates for Highway and Auto Safety. Stone added that drivers also have to operate some of the DVD players, which can cause them to lose sight of the road. "They're wonderful for keeping kids entertained on long trips, but they really do have some side consequences," she said.

Berna Diehl of Fairfax County said the side consequence she and her husband worried about was squelching their children's imaginations. "We didn't want to communicate to our kids that they needed TV round-the-clock," she said.

She also likes to catch sight of her 3-year-old and 20-month-old sons creating their own games, watching trucks and generally letting their minds wander.

But the Diehls also are modern parents, and they have a 91/2-hour drive staring them in the face at the end of July. So they think they'll rent a DVD player for the first time for that one.

"Yeah, we're kind of with the rest of society," Diehl said. "That's a lot of time to expect kids to be entertained with the license plate game."

Mikayla Booth, 3, tries to decide which movie to watch on her family's road trip. Megan Booth holds Isabelle, 1.