In 1868, the Adapazarı Municipality was officially founded on the town called Der Seadet. A sugar factory and agricultural sugar factory attracted many migrants and accelerated the industrialization of the city. A law passed on 17 June 1954 in the Grand National Assembly saw the city separated from Kocaeli Province and made the center of its own province. The 1999 Marmara earthquake affected Adapazarı and inflicted losses in lives and damage. In the 2000 official census, the population was recorded as 158 474. By official decree, the province was renamed Sakarya after the Sakarya River which runs through it.