Our readers' roundup of the best spas in the United States, Mexico, Caribbean, and Canada.

This year, our annual Spa Poll turns 21. And like any newly minted adult, it is wiser (and larger) than it was in infancy. Case in point: What began as a humble top three in 1990, with the high scorer earning a respectable 81.2, has transformed into a robust collection of 250, with the top-rated spa tipping the scales at 98.8. The winners range from a tiny two-room enclave at St. Lucia's Jade Mountain to the 100,000-square-foot behemoth Canyon Ranch in Lenox, Massachusetts. However, what hasn't changed over these past 21 years is the lofty standards to which our readers hold each candidate. Thankfully, quality is ageless.

Here, we present to you the overall score of each spa. Download the entire poll, with scores for treatments, staff, facilities, number of treatment rooms, and the cost of a basic massage.

Top 100 Resort Spas: U.S. Mainland

1. Stein Eriksen Lodge, Park City, Utah: 98.8

*20,000 square feet: the current size of the recently expanded spa at Stein Erikson Lodge. Perhaps that explains its number one position on the U.S. Resorts list.

2. Westin Riverfront Resort & Spa, Avon, Colo.: 97.5

3. Sanderling Resort & Spa, Duck, N.C.: 97.3

4. Four Seasons, Las Vegas, Nev.: 96.9

5. Ritz-Carlton Lodge, Reynolds Plantation, Greensboro, GA: 96.3

6. Stowe Mountain Lodge, VT.: 96.1