Here is a visual map from TitleMax.com that shows people are happiest (or experience the best quality of life) and where people are the saddest (or experience the worst quality of life) for each state across the US.
This information was compiled with research from countyhealthrankings.org. Following the research you can see many times that the happiest folk tend to be those living within the highest median income locations for that state and those with the worst quality of life tend to live in counties under or close to the poverty level.
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Co-founder and Vice President of SearchRank, responsible for many of the day to day operations of the company. She is also founder of The Arizona Builders' Zone, a construction / home improvement portal.