Alta/Snowbird
Alta/Snowbird has a reputation for deep, quality powder like few other places in the world. The mountains average around 500 inches of snow a year, though Alta tends to get a bit more than Snowbird. According to Forbes Traveler in 2007 and data provided by Bestsnow, Alta is the third snowiest resort in the world and Snowbird is the seventh. However, it's not just the incredible amount of snow that makes these resorts the top powder destinations in the country, it's the quality of snow. Utah is renowned for dry, lake effect powder that is featherlight and rides like air. In addition to great snow, both resorts offer plenty of big terrain with steep, expert features. Snowbird's tram flies to the top of its 3,240 feet of vertical, providing access to all kinds of world-class terrain. These resorts are listed together because an AltaSnowbird One Ticket buys access to both. Unfortunately, Alta is one of only three U.S. resorts that continues to ban snowboarders, so Alta and the combined passes are skiers only.
Grand Targhee
Though Jackson Hole receives most of Wyoming's skiing infamy, Grand Targhee receives significantly more snow. You may not experience the same amount of world-class expert terrain, but the 500-inch annual snowfall average has a way of making you forget all about it. Grand Targhee is known for the same caliber of dry, light powder as the other resorts on this list, so those 500 inches won't weigh you down. If you're having trouble finding a fresh line off the lifts, consider taking a "Snowcat Adventure" where you'll get access to 1,000 acres of uncrowded, unspoiled terrain. Alternately, if conditions aren't what you'd hoped for, return your lift ticket within an hour of purchase and get a voucher to come back another day---snow conditions so good, they're money-back guaranteed.
Steamboat
Though Steamboat's 340-inch average is modest compared to other mountains on the list, Steamboat is the destination in the country's most well-known skiing state with a reputation for having some of the driest, lightest powder anywhere. The resort coined the term Champagne Powder in recognition of the perfect powder that it receives year in and year out. While you won't find many open bowls or steeps, Steamboat has some of the best tree skiing in the world, where you'll find stashes of powder for days, making for unbelievable conditions that you'll never forget. Check out classics like Closet, Shadows and Christmas Tree Bowl to find out what Steamboat is all about.
Jay Peak
It's almost a rule that the massive mountain ranges of the western United States get far more snow than the east. Then there's Jay Peak, the rule spoiler. The only resort in the east to pull in a west-like 350-inch average of snowfall, Jay gets the type of powder that will make you forget that you're under 4,000 feet (peak elevation). Any trip to this northern Vermont gem is likely to include waking up to see the "Jay Cloud" hovering over the mountain dropping copious amounts of snow. While Jay's slopes can get windblown, its 24 glade areas are the perfect place to enjoy Mother Nature's bounty. Ski or ride knee-deep powder until your knees burn. Jay is also one of the few eastern resorts known for its rich backcountry, so if the slopes and glades are too crowded for you (unlikely), try your edges on a classic backcountry route like Big Jay.