Alaska edged out Hawaii and is now at the top of the rankings of the nation's happiest states for the first time.

The nation's largest and most northern state scored highest in the 2014 Gallup-Healthways' annual survey of well-being, with a score of 64.7 out of 100. Alaska has previously ranked among the top 10 happiest states, but this is the first year it has been the winner since the survey began in 2008.

In second place was Hawaii, which held the top spot from 2009 to 2012, but in 2013 came in eighth. The winner in 2013, North Dakota, saw a dramatic drop in its ranking, coming in 23rd in 2014. This drop was mostly due to a decline in North Dakotans' evaluation of their lives overall, and also an increase in unhealthy behaviors among the population, such as higher smoking rates and less exercise, compared with 2013, Gallup said.

The rankings are based on interviews with more than 176,000 U.S. adults in all 50 states. The researchers calculated a well-being score for each state, based on participants' answers to questions about different aspects of well-being, such as their sense of purpose, social relationships, financial lives, community involvement and physical health. [The Happiest States in 2014: Full List]

States in the Northern Plains and Mountain West tended to have higher well-being scores than states in the South and Midwest. Kentucky and West Virginia came in at the bottom of the rankings for the sixth year in a row, Gallup said.

A population's well-being is important because it is closely tied to people's health and work abilities, such as obesity rates, workplace performance and employee engagement, Gallup said.

States can implement initiatives to improve specific aspects of their residents' well-being — for example, they can work with schools, grocery stores and restaurants to include more wholesome food options, and they can work with the government and other entities to make changes that may improve community life, such as making areas more walkable or increasing the number of social activities, Gallup said.

The Gallup-Healthways Well-Being Index was conducted between Jan. 2 and Dec. 30, 2014, and its well-being score has a margin of error of about 0.1 percentage points.

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