For individual cities, the Vermont researchers note, the amount of swearing contributed substantially to their final scores. They think it's worth investigating this phenomenon, which they call "geoprofanity."
One difficulty I have with the study is that it doesn't take into account that people might just talk about happiness differently in some parts of the country or within some demographic groups. The study identified people with Norwegian ancestry as happier than African Americans. Is that because the Norwegians are actually happier or do they just tweet as if they're happier?