Move over, Hawaii. North Dakota is now the happiest state in the union.

For the first time in five years, Hawaii does not rank highest in Gallup's annual well-being poll. Instead, North Dakota takes the top spot, with a well-being score of 70.4 out of 100, according to a new report released today (Feb. 20) by the polling agency.

A state known for icy winters and oil drilling may seem like an odd candidate for the happiest place to live, especially compared to tropical Hawaii, but the upset came as no surprise to Dan Witters, research director of the Gallup-Healthways Well-Being Index.

"Historically, it's had a lot of top-10 rankings," Witters told Live Science, referring to North Dakota. "It's never been No. 1, but it's been way up there." [See List of Happiest and Saddest US States of 2013]

Aloha, Hawaii

Gallup's state rankings come from surveys of more than 176,000 Americans, including some from every state; the organization has released results annually since 2008. Survey participants answer questions about six measures of well-being: life evaluation (how people feel they're doing currently, and how they expect to do in five years); emotional health (how many positive and negative emotions they experienced in the past day); work environment (how happy they are at work and with their relationship with their bosses); physical health (including obesity and illnesses); healthy behaviors (how well people eat and how often they exercise); and basic access to food, shelter, clean water and medical care.

Hawaii has often led the pack, but in 2013, the state saw big drops in workplace satisfaction, Witters said. Specifically, Hawaiians were less likely than in previous years to say their boss treated them like a partner or created a trusting working environment. People's evaluation of their futures became less optimistic, and they felt more daily stress, anger and worry than in previous years.

Nevertheless, residents of the Aloha State need not despair. The state still ranks in the top 10 (at No. 8) and is well above average in providing residents with the basics, including health insurance. Ninety-two percent of Hawaiians have health coverage, Witters said, second only to Massachusetts' 95 percent. [7 Things That Will Make You Happy]

"It's not all bad news for Hawaii," Witters said. "In a lot of really important ways, they actually have demonstrated improvement."

North Dakota rises

North Dakota is strong across all six categories and is No. 1 for both work environment and physical health, Witters said. The Bakken oil boom, which has led to an influx of residents to the Peace Garden State, may have contributed to these ratings, he said, though the Gallup data isn't designed to analyze the causes of changes in well-being. Low unemployment caused by the boom could contribute to well-being in the form of financial security or access to health insurance, Witters said.

Well-being in the United States is also regional, with Plains states and the Mountain West strongly represented in the top 10, Witters said. South Dakota trailed North Dakota by only 0.4 points in the 2013 rankings, followed by Nebraska. Minnesota, Montana, Vermont, Colorado, Hawaii, Washington and Iowa rounded out the top 10.

At the bottom of the pack were the "usual suspects," Witter said. West Virginia came in dead last, as it has for five years running. Other bottom-10 states were also mostly in the South or industrial Midwest: Kentucky, Mississippi, Alabama, Ohio, Arkansas, Tennessee, Missouri, Oklahoma and Louisiana.

Trending states

The rankings show that being "easy on the eyes" isn't the only thing that matters for happiness, Witters said. California, for example, is a much-loved tourist destination but ranks pretty consistently at the lower end of the top third. (This year, it's number 17.) Nebraska, on the other hand, is on few must-see lists but constantly ranks among the top 10 states for well-being.

Since 2010, the first full year after the Great Recession's end, 11 states have improved in well-being every year: Nevada, Montana, Vermont, Nebraska, Iowa, Maine, Arizona, Wisconsin, Mississippi, Texas and California. Of those, Montana, Vermont, Nebraska and Iowa are especially noteworthy for being top-10 states still making gains, Witters said.

Several factors distinguished high-well-being states from their struggling counterparts, Witters said. People in happy states are healthier, smoke less and report learning new things every day. They have safe places to exercise and feel they are partners to, not underlings of, their bosses. They also take better care of their teeth. Access to dentistry, Witters said, is a strong predictor of health and well-being.

Follow Stephanie Pappas on Twitter and Google+. Follow us @livescience, Facebook & Google+. Original article on Live Science.