Clarington (2021 population 101,427) is a lower-tier municipality in the Regional Municipality of Durham in Ontario, Canada. It was incorporated in 1973 as the town of Newcastle with the merging of the town of Bowmanville, the Village of Newcastle and the townships of Clarke and Darlington, and was established on January 1 1974. In 1993, the town was renamed Clarington, a portmanteau of the names of the two former townships. Bowmanville is the largest community in the municipality and is the home of the municipal offices.