Resident Population in Trinity County, CA was 15.64200 Thous. of Persons in January of 2024, according to the United States Federal Reserve. Historically, Resident Population in Trinity County, CA reached a record high of 16.10200 in January of 2021 and a record low of 7.61500 in January of 1970. Trading Economics provides the current actual value, an historical data chart and related indicators for Resident Population in Trinity County, CA - last updated from the United States Federal Reserve on April of 2026.