And then there were three.

Taos Ski Valley, one of the last bastions of snowboard-free skiing, caved to commercial pressure last week and said it will allow snowboarders on the slopes starting at the end of the season. For the family that owns the storied resort, it's an effort to expand the business and retain customers whose children or grandchildren prefer snowboards to downhill skis. But it's a crushing defeat for some lifelong Taos fans, who now are threatening to pack up and sell their New Mexico real estate.

It leaves just three major resorts standing against the snowboarding juggernaut: Alta and Deer Valley in Utah, and Vermont's Mad River Glen.

Relations between skiers and riders (as snowboarders are known) have never been chillier. An age gap helps put the groups at odds.

The majority of skiers who skied more than a day at a U.S. resort this past year were older than 25, according to the National Ski Areas Association; the majority of snowboarders weren't old enough to rent a car. The divide has led each side to generalize about the other: Boarders cast skiers as old, stuffy and conservative; skiers say boarders are young, reckless and rowdy.

Taos, built to resemble Switzerland's St. Moritz, opened in 1955 and is known for its steep terrain, gorgeous scenery and laid-back vibe. Skiers fuel the local economy, buying art, real estate and fancy dinners.

Some locals say boarders won't bring the same kind of money to town. "They bring their lunch to the mountain instead of buying it," says Liz Jamison, a real estate agent and ski instructor at Taos for 22 years.

The announcement "Opens to Snowboarding March 19, 2008," appeared last week in red letters on Taos Ski Valley's Web site; a snowboarder's silhouette still obscures the word "ski" in the slogan "Ski Taos." Within hours, hundreds of people had posted comments, ranging from "How can this happen?" and "NNNOOOOOO!!!!" to "Bout time!" and "This world is so full of prejudice and hate, why bring it into the world of snow sports?"

But with ski revenue sliding and offspring of even the most hard-core skiers gravitating to boards, skiers-only destinations find it hard to keep refusing. Skier and snowboarder visits dropped in the 2006-07 season to a combined 55 million, from close to 59 million in 2005-06, the national ski areas group says. Industry revenue of $4.9 billion in 2005-06 was down slightly from the previous season, according to the group's latest data.

To boost sales, Aspen Mountain began allowing snowboards in 2001; now 10 percent of visitors there come to snowboard. Keystone in Colorado, Park City Mountain Resort in Utah and California's Alpine Meadows began admitting snowboarders more than 10 years ago; now 30 percent of visitors to Alpine Meadows are snowboarders.