Bettendorf is a city in Scott County, Iowa, United States. It is the 15th largest city of Iowa and the third-largest city in the "Quad Cities". It is …Bettendorf is a city in Scott County, Iowa, United States. It is the 15th largest city of Iowa and the third-largest city in the "Quad Cities". It is part of the Davenport–Moline–Rock Island, IA-IL Metropolitan Statistical Area. The population was 39,102 at the 2020 census.