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.
The chart below shows how state rankings changed between 2012 and 2013:
Gallup compiled its state-level well-being data based on more than 178,000 interviews with American adults across all 50 states, conducted from January-December 2013.
You can find Gallup's full report here.
This article originally appeared on Business Insider.