There are a total of 3 counties in the state of Delaware. Among them, New Castle County is the oldest one (established in 1664) while Kent County is the youngest (established in 1680). With population of 538,479, New Castle County is the most populated. The biggest county by land area is Sussex County (3,098 km2) and the smallest is New Castle County (1,279 km2). Below please see all Delaware counties which are listed in alphabetical order.
Map of Delaware Counties