Delaware (dĕlˈəwâr, –wər) [key], city (1990 pop. 20,030), seat of Delaware co., central Ohio, on the Olentangy River; inc. as a city 1903. A trade center in a fertile farm area, it also has some manufacturing. Ohio Wesleyan Univ. is in Delaware, which is also the birthplace of President Rutherford B. Hayes. During the War of 1812, the city served as Gen. William Henry Harrison's headquarters.