SIOUX FALLS, S.D. (MITCHELLNOW) It’s all smiles in Sioux Falls. That’s according to a new study ranking Sioux Falls the fourth happiest city in America. WalletHub compared 182 of the largest cities — including the 150 most populated cities — plus at least two of the most populated cities in each state across three key factors. Those are emotional and physical wellbeing, income and employment, and community and environment. Rapid City also made the list at number 33.