​Which state is the happiest in the U.S.? A new poll measuring each state's well-being might surprise you.

"According to Gallup's annual well-being poll the honor belongs to — North Dakota, the Peace Garden State." (Via NBC)

North Dakota scored a 70.4 out of 100 — even beating Hawaii, the poll's top state the previous four years. The other Dakota came in a close second. (Via Flickr / Tim EvansonFlickr / Vatsek)

​The Aloha State placed eighth this time because of a significant drop in workplace satisfaction. (Via KGMB)

And the unhappiest states — West Virginia bottomed the list for the fifth straight year, followed by Kentucky and Mississippi. (Via WTXF)

So how exactly are these results determined? Well, Gallup interviewed more than 178,000 people from all over the country about their lives. The well-being score measures six areas involving work environment as well as physical and emotional health.

If you're wondering what makes North Dakota such a happy place to be, we have a few guesses.

According to Everyday Health, a New York professor thinks it might be because of North Dakota's agricultural presence. He says more time spent outdoors and greater physical activity all are known to have positive health effects.

And a Gallup researcher tells The Huffington Post the state's recent oil boom has created many jobs, giving residents greater financial security. ​

Regarding the nation's well-being as a whole, the U.S.' score fell slightly this year, matching a previous low in 2011.