Most mornings, Margarita Dreyer wakes up around 7 a.m. and gets right to her exercises—stretches, strengthening reps, and pushups. She golfs at least twice a week, skis in Vail, CO, each winter, and regularly parties with her friends. Did we mention the retired furniture import business owner is 85?

“I never even think of age. ... I take care of myself," says Dreyer, who credits her good health to a lifetime of positive thinking, a mostly plant-based diet, plenty of exercise, great friendships—and perhaps most of all, the town of Tiburon, in California's Marin County, where she's lived the past 30 years.

“In Marin, usually you find people who are very interested in theater, and opera, and exercise and entertaining. It's all part of what is important in life."

In America, the median life span is nearly 79 years, according to the U.S. Centers for Disease Control and Prevention. But that's not universal. There are pockets of the Deep South and the Dakotas where a storm of socioeconomic factors lowers life expectancy to 68 years or less. But then there's the other side of the equation: the special places where people regularly blow right past 80, healthy and active, and just keep on going.

The data team at realtor.com® set out to find these American fountains of youth. We located the 10 counties where people are living the longest, and then took a deep dive to find out what differentiates them from the rest of the country.

“If you want to live a long time, the best thing you can do is move to a place where people are verifiably living the longest," says Dan Buettner, founder of Blue Zones, an initiative that works with communities to help set up wellness policies to increase the life span of residents.

Buettner has spent his career researching the places around the world where people live the longest. The five so-called blue zones are Okinawa, Japan; Sardinia, Italy; Nicoya, Costa Rica; Icaria, Greece; and Loma Linda, CA.

Sardinia, Italy, is one of the five
Sardinia, Italy, is one of the five "blue zones" where people live the longest.

Levranii/iStock

He found certain commonalties, ranging from a tradition of veggie-rich diets and exercise, to highly social or faith-based communities. So Buettner and his team set out to make America more blue—helping towns work toward Blue Zone certification, for which residents, schools, grocery stores, restaurants, and workplaces institute healthier practices. The project was piloted in Albert Lea, MN, in 2009 and has since spread to other states.

Buettner contends that our habits—destructive or healthy—are shared by fellow community members. So if your neighbors are hiking on weekends or cycling to work, you're more likely to do the same. By the same token, "if you drive into a neighborhood and you see McDonald's and KFC billboards ... you shouldn’t live in that neighborhood," Buettner says.

To come up with the longevity list, we used data from the Institute for Health Metrics and Evaluation at the University of Washington, in Seattle, which looked at death certificates in every U.S. county in 2014 to calculate the life expectancy from birth. We also added population data from the Census Bureau and home price data from realtor.com.

Then we interviewed health experts, residents, business owners, and real estate experts to figure out why life expectancies stretch so long in these places. (The ranking was limited to just one county per state to for geographic diversity.)

Our places run the gamut in income, real estate value, population size, and scenery. But most of them are friendlier places where people tend to know your name. Get used to it.

Counties with longest life expectancy
Counties with longest life expectancy

Claire Widman

1. Summit County, CO

Population: 30,585
Notable city: Breckenridge, CO
Median life span: 86.8 years
Median home list price: $930,500

Main Street in Breckenridge, CO
Main Street in Breckenridge, CO

bauhaus1000/iStock

The first time Jeff Carlson visited the ski town of Breckenridge, CO, in 2001, he was smitten with the backcountry skiing, hiking, and the glorious Rocky Mountains. Within days he decided to decamp from New York, and he hasn't looked back since. These days when Carlson, now 37, isn't at work as general manager of Mountain Outfitters, a ski equipment store, you can find him fly fishing with his dog, Takoda.

“People move to Summit County because they value recreation and outdoors,” Carlson says, adding that people here “value [outdoor] minutes over money.”

An active, outdoorsy lifestyle coupled with healthier diets may be the county's secret to longevity. There isn't a single fast-food joint in the county's main city of Breckenridge, 2½ hours northwest of Aspen.

Living in the area isn't cheap, though. The median home list price is $799,000 just in Breckenridge, according to realtor.com data. But real estate varies from multimillion-dollar vacation homes with perks such as bar areas and home theaters with sound systems to more modest two-bedroom condos that start around $350,000 and go up from there.

2. Billings County, ND

Population: 940
Notable city: Medora, ND
Median life span: 84 years
Median home list price: $331,200

Billings County courthouse in Medora, ND
Billings County courthouse in Medora, ND

public domain

Billings County is a small ranching community in the most rural reaches of western North Dakota, where the Great Plains joins the Badlands. It's an outdoorsy kind of place where most folks hunt and fish in their spare time.

The county's main attraction is the Old West town of Medora, population 132, a tourist destination that's very much a blast from the past.

"Long life is not unusual here," says Douglas Ellison, 55, who owns a bookstore and an inn with his wife in Medora. He notes there are active residents in their 90s and one rancher who's now over 100.

“The ranchers still do the physical labor," he says. "The townspeople walk a lot. Everyone stays physically active.”

The clean air and lack of common stressors found in big cities may also be factors.

"We're not fighting traffic every day," Ellison adds. In fact, there's not even a single grocery store in town. Locals travel about a half-hour west to Dickinson to do their shopping.

Much of the county is made up of federal- or state-owned land—it's home to Theodore Roosevelt National Park, where the former president famously hunted bison.

3. Marin County, CA

Population: 260,651
Notable city: San Rafael, CA
Median life span: 83.8 years
Median home list price: $1,425,400

Sausalito, CA, in Marin County
Sausalito, CA, in Marin County

sestevens/iStock

Affluent Marin, just north of San Francisco, was named the healthiest county in the state by the Robert Wood Johnson Foundation and the University of Wisconsin Population Health Institute. That's no easy feat in health-obsessed California.

But the county's more progressive laws—such as its 2015 ban on wood-burning heaters, which pose health risks, and prohibiting public smoking a year later—are a testament to the area's commitment to healthy living. There's also an abundance of doctors here, with one primary care physician for every 630 residents and one mental health care provider for every 140 residents.

“Marin has policies that make the healthy choice the easy choice,” Buettner says.

The area's close proximity to San Francisco, top-notch schools, and low crime rate—as well as its breathtaking vistas and world-class biking and hiking— are big draws for new residents, says Jonathan Marks, a real estate agent at Alain Pinel Realtors. But buyers need to pony up for those perks: The median home list price is well over $1 million.

4. Fairfax County, VA

Population: 1,148,433
Notable city: Herndon, VA
Median life span: 83.7 years
Median home list price: $608,700

Lake Audubon in Reston, VA, in Fairfax County
Lake Audubon in Reston, VA, in Fairfax County

krblokhin/iStock

The Washington, DC, suburb of Fairfax County has gone bike-crazy. With miles of new cycling lanes added over the past few years, more and more residents are increasingly choosing to pedal to work.

“There 's been a big boom in riding,” says Bernard Etherly, a manager at Performance Bicycle, a shop in Springfield, part of Fairfax County. He says bike commuters quickly realize the health benefits: “They start to lose weight; their blood pressure and cholesterol goes down.” What's not to love?

But biking isn’t the only reason folks are healthier here. The county is home to many affluent, well-educated residents. Nearly two-thirds have completed a bachelor's degree or higher, compared with 34% nationally, according to the U.S. Census Bureau. More educated folks often make healthier choices—and may be able to afford to eat better.

Housing in the county ranges from very reasonably priced mobile homes under $70,000 and two-bedroom condos going for less than $150,000 to sprawling, eight-figure mansions with in-ground pools, heated floors, and wine cellars.

(Note: The city of Fairfax, VA, is separate from Fairfax County, although the county surrounds the city.)

5. Aleutians East Borough, AK

Population: 3,370
Notable city: King Cove, AK
Median life span: 83.7 years
Median home list price: $226,500

King Cove, AK
King Cove, AK

facebook.com/ AleutiansEastBorough

Modern life has passed Aleutians East Borough by in many ways. The only way on or off these sparsely inhabited islands, stretching far from mainland Alaska to the Pacific, is by boat or plane. And a plane trip from Anchorage can cost more than $3,000. Maybe it's not surprising that some of the Alaska Natives, whose ancestors settled here thousands of years ago, have never left the islands.

"They do not have a newspaper, or any of the standard city features," says real estate agent Linda Friday of Jack White Real Estate, based in Anchorage. She's had a listing for a three-bedroom home on an acre lot in the main town of King Cove sit on the market for two years due to a lack of buyers. "You have a very hardy people who live and work there."

Peter Pan Seafoods has a processing facility on King Cove where many of the locals work. There are a few small food stores, but most of the locals also hunt and fish for their dinner.

"They're living off the land," says Jimmy Sparks, a real estate agent at Real Estate Brokers of Alaska, based in Anchorage. "It's a whole other lifestyle."

6. Presidio County, TX

Population: 7,156
Notable city: Marfa, TX
Median life span: 83.7 years
Median home list price: $297,000

Cibolo Creek in Marfa, TX
Cibolo Creek in Marfa, TX

Stevens Fremont/Getty Images

Texas' Presidio County, which sits along the U.S.-Mexico border in the Chihuahuan Desert, is one of the more puzzling counties on our list. It's rural with a median household income of just $33,453—not a combo most would associate with longevity.

"Lots of beans and tortillas, I guess," jokes Brad Newton, executive director of the Presidio Municipal Development District, an economic development group in the city of Presidio.

Like many of the locals, Newton lives in an adobe home that keeps temperatures cooler in the summer. "We're so far from a hospital, we can't afford to get sick," he says.

The predominantly Hispanic families and communities in Presidio County are extremely close-knit—an important factor in personal well-being.

And, like most of the places on this list, there's a strong outdoor appeal to Presidio. The largest park in Texas, the 300,000-acre Big Bend Ranch State Park, offering about 240 miles of hiking, biking, and horseback riding trails, is within its borders.

The county is also home to the small, artsy town of Marfa. It attracts tourists from all over the world who visit the Chinati Foundation, a contemporary fine art museum.

“It’s being out in a really wild place and keeping people close to you,” says Mary Farley, a real estate agent at Marfa Vista Real Estate. "That helps with longevity."

7. San Juan County, WA

Population: 16,715
Notable city: Friday Harbor, WA
Median life span: 83.7 years
Median home list price: $774,400

Sea kayakers near Orcas Island in Washington's San Juan County
Sea kayakers near Orcas Island in Washington's San Juan County

Joel W. Rogers/Getty Images

Those looking for proof that there's something really special about the islands of San Juan County should note that Oprah Winfrey reportedly bought an $8 million retreat on the county's Orcas Island last month. North of Seattle, scenic San Juan is known as a vacation retreat for rich buyers seeking a bit of peace and tranquility, some of Washington's natural beauty, and just maybe the secret to living long.

“There's a lot of wealth up here, but it's unassuming. You can be standing next to a millionaire and not know it,” says Merri Ann Simonson, a real estate broker at Coldwell Banker San Juan Islands. The housing ranges from cabins nestled in the woods starting around $200,000 to mansions that have ocean views and private orchards.

Buyers may come for the beauty, but they stay for the county’s civic-mindedness, another factor that may contribute to longer lives. Many residents are involved with local nonprofit groups such as the San Juan Preservation Trust. And being in a seaside community may help residents and visitors to unplug and relax.

“When you’re out kayaking or out on the boat shrimping or fishing, you aren’t stressed out,” Simonson says.

8. Los Alamos County, NM

Population: 18,738
Notable city: Los Alamos, NM
Median life span: 83.5 years
Median home list price: $384,400

Homes in Los Alamos, NM
Homes in Los Alamos, NM

benedek/iStock

The nuclear weapons used during World War II were designed by physicists in Los Alamos. Today, this New Mexico county still has a large research presence, including the Los Alamos National Laboratory. And as a result of this highly skilled economy, locals tend to be well-off, never a bad thing when it comes to life spans.

This year, Los Alamos County was ranked the fourth healthiest community in the nation by U.S. News & World Report. The numbers tell the tale: Only 11.2% of residents smoke, just 5.8% have no health insurance, and nearly 88% are active in their leisure time. That's compared with national rates of 17.3%, 12.9%, and 75.5% respectively.

It's not hard to stay active, with skiing just a hop away at Pajarito Mountain, and two national parks right outside the county: Bandelier National Monument and the Valles Caldera National Preserve.

“Many of the scientists and researchers who are attracted to work at the laboratory are equally attracted to this kind of healthy lifestyle,” says Julie Habiger, spokesperson for Los Alamos County.

9. Teton County, WY

Population: 23,265
Notable city: Jackson, WY
Median life span: 83.5 years
Median home list price: $1,305,200

The antler arches in Jackson Hole town square
The antler arches in Jackson Hole town square

troutfisherman/iStock

Every year millions of tourists flock to Teton County to visit Jackson Hole, one of the world's most popular ski resorts, and Yellowstone National Park, which is partly located in the county. The combo of wealth, mountain air, and outdoor activities may be the reason that residents are in such good shape.

After graduating from Presbyterian College 17 years ago, Andrew Ellett came to Jackson Hole. He figured he’d spend the summer backpacking before heading off to grad school. But he enjoyed the lifestyle so much that, after meeting his future wife, he decided to stay put.

“People are here for the beauty, the serenity, a simpler life outside of the city,” says Ellett, who is now a real estate broker at Engel & Völkers Jackson Hole. Once a year, he and a friend do a three-night canoe and camping trip in the county. They don’t get cellphone service and go days without seeing a single person. And that's just fine. “More than anything [we're here for] the lifestyle,” he says.

10. Collier County, FL

Population: 372,880
Notable city: Naples, FL
Median life span: 83.4 years
Median home list price: $479,400

Sunset crowd and swimmers in Naples, FL
Sunset crowd and swimmers in Naples, FL

benedek/iStock

Retired advertising executive Steve Calabrese, 70, and his wife hope to soon call Collier County home. The couple are betting that the warm weather and the programs provided by the Parkinson's Association of Southwest Florida in Naples will help her battle the disease. Naples is the largest city in the county on the western coast of Florida across from Miami.

The Calabreses are just waiting to sell their single-family home in Nantucket, MA, before downsizing into a three-bedroom condo near the beach in Naples.

Choosing Collier County as a place to get healthier isn't a far-fetched idea. Of all of the counties with the highest life expectancies, only Collier County is up for consideration to become a Blue Zone. That's partly due to NCH Healthcare System in Naples.

“The hospital [system] is one of the best in the country. Especially for older residents, access to health care becomes really important,” says Buettner, adding that NCH even does the little things right, like offering better-quality food in its cafeterias. “Not the usual hamburgers, hot dogs, or mashed potatoes."

“I always thought of Florida as a place where old people went to wait around and die,” says Calabrese, who looks forward to the beach and the fitness centers in Naples. "But now I see it as a place to be as active as you want."

Clare Trapasso contributed to this report.