New Castle County is the northernmost of the three counties of the U.S. state of Delaware. As of the 2020 census, the population was 570,719, making it the most populous county in Delaware, with nearly 60% of the state's population of 989,948. Wikipedia
Cities: New Castle, Wilmington, Newark, and more
Population: 575,494 (2022)
Area: 494 mi²
Congressional district: At-large
Founded: August 8, 1673
Largest city: Wilmington
Named for: William Cavendish, 1st Duke of Newcastle