Largest Counties in Delaware

Delaware only has three counties: New Castle, Kent, and Sussex.


1. New Castle County

County Facts:

  • Population: Approximately 570,000
  • Area Codes: 302
  • Zip Codes: 19701–19720, 19801–19810
  • County Seat: Wilmington

Geography and History:

New Castle County is located in the northernmost part of Delaware and covers 494 square miles. The county’s geography is diverse, with the hilly Piedmont region in the north and flat coastal plains in the south. The Christina River, Delaware River, and several tributaries flow through the area, making it a key waterway region for commerce and industry. The climate is temperate, with four distinct seasons.

Established in 1673, New Castle County is the most populous and economically important county in Delaware. Wilmington, the largest city in the state, became a key industrial hub due to its location on the Delaware River. Throughout its history, the county was influenced by Dutch, Swedish, and English settlers, each contributing to its cultural fabric. Today, the county is a financial and corporate powerhouse, home to major banks and corporations.

Colleges and Universities:

  • University of Delaware: Located in Newark, it is the largest public university in the state, offering undergraduate and graduate programs across various fields.
  • Wilmington University: A private university providing undergraduate, graduate, and doctoral programs, with campuses throughout the state.
  • Delaware Technical Community College (Stanton and Wilmington Campuses): Provides associate degrees and certificate programs, offering accessible education to residents.

Major Landmarks:

New Castle County is home to numerous historic and cultural landmarks, including the Hagley Museum, which showcases the early industrial development along the Brandywine River. The Nemours Mansion and Gardens is a stunning 300-acre estate built by Alfred I. du Pont. Other notable sites include the Delaware Art Museum and the Historic New Castle district, known for its well-preserved colonial architecture.


2. Kent County

County Facts:

  • Population: Approximately 184,000
  • Area Codes: 302
  • Zip Codes: 19901, 19904, 19934, 19977, 19962, 19938, 19979
  • County Seat: Dover

Geography and History:

Kent County is located in central Delaware, covering 800 square miles of predominantly flat terrain, typical of the coastal plains. The county is bordered by the Delaware Bay to the east and is intersected by several rivers and creeks, including the St. Jones River. Its temperate climate features warm summers and mild winters, making it ideal for agriculture.

Kent County was established in 1680 and has long been an agricultural heartland in Delaware. The county seat, Dover, was founded in 1683 by William Penn and has been the capital of Delaware since 1777. Dover is known for its role in Revolutionary War history and as a political and governmental center. Over time, Kent County has diversified its economy beyond farming, with a significant military presence, including the Dover Air Force Base.

Colleges and Universities:

  • Delaware State University: A historically black public university located in Dover, offering undergraduate, graduate, and doctoral programs.
  • Wesley College (now merged with Delaware State University): Previously a private liberal arts college, now part of DSU’s offerings.
  • Delaware Technical Community College (Terry Campus): Offers associate degrees, technical training, and certificates, serving the central Delaware population.

Major Landmarks:

One of the key landmarks in Kent County is the Dover International Speedway, known for hosting NASCAR races and attracting visitors nationwide. The Air Mobility Command Museum, located at the Dover Air Force Base, provides an in-depth look at military aviation history. Dover’s Legislative Hall is the seat of Delaware’s government, and nearby, the First State Heritage Park offers tours of colonial-era buildings. The John Dickinson Plantation, the home of one of the founding fathers, is another significant historical site.


3. Sussex County

County Facts:

  • Population: Approximately 251,000
  • Area Codes: 302
  • Zip Codes: 19930–19975
  • County Seat: Georgetown

Geography and History:

Sussex County is the largest county in Delaware by land area, covering 1,196 square miles. It is located in the southern part of the state and is characterized by flat, sandy terrain with numerous wetlands, rivers, and bays. The county is bordered by the Atlantic Ocean to the east, with several popular beach towns lining the coast. Sussex County experiences a humid subtropical climate, with warm, humid summers and mild winters.

Sussex County was one of the first areas in Delaware settled by Europeans, beginning with the Dutch in 1631. The county has a long agricultural history, with poultry farming being a dominant industry. Georgetown, the county seat, was established in 1791 and is centrally located to provide easier access for all county residents. Sussex has since evolved into a hub for tourism and agriculture, particularly in the coastal areas, which draw thousands of visitors each year to its beaches.

Colleges and Universities:

  • University of Delaware (Georgetown Campus): Provides agricultural education and research programs focused on the unique needs of Sussex County.
  • Delaware Technical Community College (Georgetown Campus): Offers associate degrees, technical training, and career certifications in various fields.
  • Wilmington University (Georgetown Campus): Provides flexible undergraduate and graduate programs tailored to working adults in southern Delaware.

Major Landmarks:

The Delaware Beaches, including Rehoboth Beach, Bethany Beach, and Fenwick Island, are some of the county’s most iconic landmarks, attracting visitors for their pristine sands and family-friendly atmosphere. Cape Henlopen State Park, with its historic lighthouse and scenic coastal landscapes, is a favorite for outdoor enthusiasts. The Nanticoke Indian Museum, the only Native American museum in Delaware, offers insights into the region’s indigenous history. Georgetown’s Circle and the annual Return Day festival are unique to Sussex, where residents celebrate election outcomes with a traditional burying of the hatchet ceremony.