Delaware Counties. List Alphabetically (and by Population)

How many counties are there in Delaware? As of 2024, 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).

Largest Counties in Delaware

1. New Castle County

County Seat: Wilmington

  • Area: 494 square miles
  • Population: Approximately 570,719 (2020 census)
  • Area Codes: 302
  • Latitude: 39.7459° N
  • Longitude: 75.5466° W

Location and History

New Castle County is the northernmost and most populous county in Delaware. It was established in 1673 and is the largest economic and cultural center in the state. Wilmington, the county seat, is Delaware’s largest city and was founded by Swedish settlers in 1638 as Fort Christina, the first permanent European settlement in the Delaware Valley. The county’s strategic location along the Delaware River and its proximity to major cities like Philadelphia and Baltimore have historically made it a hub for trade, industry, and finance. The county is home to many historic sites, reflecting its long and rich history, from colonial times through the Industrial Revolution and into the present day.

Major Highways and Landmarks

New Castle County is served by several major highways, including Interstate 95, which runs north-south through the county and connects it to Philadelphia and Baltimore. Other important routes include Interstate 295, which provides access to New Jersey via the Delaware Memorial Bridge, and U.S. Route 13, which runs parallel to I-95. Significant landmarks include the Hagley Museum and Library, which preserves the site of the original DuPont gunpowder mills and offers insights into early American industrial history. The Nemours Mansion and Gardens, a 300-acre estate with a stunning French-style mansion, is another key attraction. The county is also home to the Delaware Art Museum, known for its collection of American art and illustration, and the Wilmington Riverfront, a vibrant area of parks, restaurants, and entertainment venues along the Christina River.

2. Sussex County

County Seat: Georgetown

  • Area: 1,196 square miles
  • Population: Approximately 237,378 (2020 census)
  • Area Codes: 302
  • Latitude: 38.6901° N
  • Longitude: 75.3850° W

Location and History

Sussex County is the southernmost and largest county in Delaware by area. It was established in 1683 and is known for its agricultural heritage, beautiful beaches, and historic towns. Georgetown, the county seat, was founded in 1791 specifically to serve as the county’s administrative center due to its central location. The county’s economy has traditionally been based on agriculture, particularly poultry farming, but tourism has become increasingly important, especially in coastal areas such as Rehoboth Beach, Lewes, and Bethany Beach. Sussex County also has a rich colonial history, with many sites dating back to the early European settlements in the 17th century.

Major Highways and Landmarks

Sussex County is served by U.S. Route 13, which runs north-south through the county, and U.S. Route 9, which provides access to the Delaware beaches. State Route 1 is another key highway, running parallel to the coast and connecting the beach towns. Major landmarks in Sussex County include the historic town of Lewes, often referred to as “The First Town in The First State,” where the earliest European settlers in Delaware arrived. The Cape Henlopen State Park, with its stunning beaches, hiking trails, and World War II-era observation towers, is another major attraction. The county is also known for its vibrant arts scene, especially in Rehoboth Beach, which hosts the annual Rehoboth Beach Independent Film Festival and has numerous galleries and cultural events.

3. Kent County

County Seat: Dover

  • Area: 800 square miles
  • Population: Approximately 181,851 (2020 census)
  • Area Codes: 302
  • Latitude: 39.1582° N
  • Longitude: 75.5244° W

Location and History

Kent County is located in central Delaware and is the smallest of the state’s three counties by area. It was established in 1680 and named after Kent, England. Dover, the county seat, is also the capital of Delaware and was founded in 1683 by William Penn. The county’s history is deeply tied to its role in the early colonial government and later as a key location during the American Revolution. Dover is home to many historic buildings and sites, including Legislative Hall, where Delaware’s General Assembly meets. Kent County’s economy has traditionally been based on agriculture, with crops like corn, soybeans, and wheat, though it has diversified in recent decades.

Major Highways and Landmarks

Kent County is served by U.S. Route 13 and State Route 1, both of which run north-south through the county, connecting Dover with Wilmington to the north and the beach areas to the south. U.S. Route 113 also provides an alternative route through the county. Major landmarks include the Dover Air Force Base, one of the largest military airlift installations in the United States, and the Air Mobility Command Museum, which offers a look at the history of military aviation. The Old State House in Dover, which dates back to 1791, is a key historical site, as is the John Dickinson Plantation, the boyhood home of one of the founding fathers of the United States. The county also hosts the annual Delaware State Fair in Harrington, a major event celebrating the state’s agricultural heritage.

List of All Counties in Delaware Alphabetically

Below please see all Delaware counties which are listed in alphabetical order.

  1. Kent County, DE
  2. New Castle County, DE
  3. Sussex County, DE

Map of Delaware Counties

Map of Delaware Counties