Resident Population in Twin Falls County, ID was 96.50900 Thous. of Persons in January of 2024, according to the United States Federal Reserve. Historically, Resident Population in Twin Falls County, ID reached a record high of 96.50900 in January of 2024 and a record low of 41.80700 in January of 1970. Trading Economics provides the current actual value, an historical data chart and related indicators for Resident Population in Twin Falls County, ID - last updated from the United States Federal Reserve on April of 2026.