Gallup measures happiness, or well-being, on a set of six sub-indexes, which individually examine life evaluation, emotional health, work environment, physical health, healthy behaviors, and access to basic necessities.
Here are the 10 states with the highest and lowest levels of well-being, according to Gallup:
How did North Dakota move so far up in the rankings? According to Gallup, it also ranked as the top state in two of the six sub-indexes: work environment and physical health.
North Dakota has experienced a serious boom in job growth: For the fifth year in a row, that state topped all other states in employee perceptions of job creation at their workplaces in 2013, as measured by the Gallup Job Creation Index.