The tiny island of Nantucket, Massachusetts, is home to some 14,000 year-round residents. Joining their ranks will cost you at least $1 million, according to a new list of luxury housing markets by Realtor.com.

Nearly all of Nantucket’s active listings are priced at $1 million or higher with a median listing price of $4.08 million, the real estate platform found. The island averages 138 million-dollar listings a year, according to the report.

Vineyard Haven, a community within neighboring Martha’s Vineyard, Massachusetts, has the second-highest concentration of million-dollar listings at 90% of the active listings with a median listing price of $2.4 million. Jackson, the principal town of the Jackson Hole valley in Wyoming, boasts the third-highest median price at $1.75 million.

Realtor.com identified 13 U.S. housing markets where at least half of active listings were priced above $1 million but with fewer than 500 such listings. Anthony Smith, senior economist at Realtor.com, said the list was designed to highlight “pure luxury” markets rather than areas that happen to reflect high regional housing costs.

Most of these housing markets are defined by scarcity, according to Smith. The frontrunners, Nantucket and Vineyard Haven, are prime examples as they’re both located on islands.

“You have finite land, strict building and preservation codes, and that combination sets a real premium on what’s available,” he said.

This scarcity applies to non-coastal hubs such as Jackson, too, he said, where land is abundant but much of it is earmarked for conservation. Only 3% of land in Jackson Hole is privately owned.

While five of the luxury hubs identified by Realtor.com are in California, the rest are scattered across the country, from Kapaa, Hawaii, to Hailey, Idaho. A notable inclusion on the list is Petoskey, Michigan, where 53% of active listings are priced over $1 million. While it doesn’t carry the same name recognition as Nantucket or Napa, the Lake Michigan town checks a lot of boxes for deep-pocketed buyers, Smith said.

“When you look at what defines a luxury market, it’s all there: waterfront views on Little Traverse Bay, ski access in the winter, resort-style living,” he said.

He added that Petoskey is one of the more affordable markets on the list with a median listing price of $1.1 million.

The top 1% of Petoskey homes — representing the ultra-luxury market — start at just under $8 million, while the same threshold starts at nearly $59.2 million in Rifle, Colorado (also on Realtor.com’s list), about 70 miles away from Aspen.

While high-income consumers are propping up spending in travel and other categories, the luxury housing market is showing signs of softness like the overall housing market, according to Smith.

The luxury threshold, or 90th percentile of homes, stood at $1.25 million nationally in March, down 2.9% year over year, while the overall median price is down 2.2% annually, according to Realtor.com.

Prices are firming up into the spring across the housing spectrum, however, with the luxury threshold up 3.7% and the overall market rising 3% from February.