Resident Population in Marengo County, AL was 18.51200 Thous. of Persons in January of 2024, according to the United States Federal Reserve. Historically, Resident Population in Marengo County, AL reached a record high of 25.40000 in January of 1977 and a record low of 18.51200 in January of 2024. Trading Economics provides the current actual value, an historical data chart and related indicators for Resident Population in Marengo County, AL - last updated from the United States Federal Reserve on April of 2026.