The happy rank is actually rather inconsistent i think. And as noted, “Happiness” data is derived from two data sets. One included subjective personal reports of happiness, while the other included objective measures, such as state population density, air quality, home prices + other factors known to normally impact quality of life. However, the latter method would not necessarily denote the happiest people.
High population density is strongly correlated with leftism. People living in closer quarters experience more envy so are drawn into the politics of envy. Cities are Democrat factories, the suburbs and beyond Republican. Democrats hate the suburbs, which are still in their visual range, and want to restrict them to reduce their painful feelings of envy.