About New Castle County
New Castle County is a mid-sized city located in United States, in the Delaware region. According to the latest available data (2026), the population of New Castle County is approximately 570,719 residents, making it the #122 most populous city in United States.
Globally, New Castle County ranks #3,256 among the world's most populated cities.
New Castle County City Statistics
| City | New Castle County |
| Country |  United States |
| Population | 570,719 |
| Global Rank | #3,256 |
| Rank in United States | #122 of 867 cities |
| City Category | mid-sized city |
| Region | Delaware |
| Latitude | 39.58 |
| Longitude | -75.64 |
| Data Year | 2026 |
Population Comparison
To put New Castle County's population of 570,719 into perspective:
- New Castle County has over 570,000 residents.
Where is New Castle County Located?
New Castle County is located in United States, in the Delaware region, at coordinates 39.58° latitude and -75.64° longitude. New Castle County sits in the subtropics, typically enjoying warm temperatures year-round.
Nearby Cities
Other Cities in United States
Largest Cities in United States
| # | City | Population |
|---|---|---|
| 1 | Harris County | 4,731,145 |
| 2 | Los Angeles | 3,898,747 |
| 3 | San Diego County | 3,298,634 |
| 4 | Brooklyn | 2,736,074 |
| 5 | Miami-Dade County | 2,701,767 |
Frequently Asked Questions
What is the population of New Castle County?
The population of New Castle County is approximately 570,719 residents according to the latest available data (2026).
Where is New Castle County located?
New Castle County is located in United States at approximately 39.58° latitude and -75.64° longitude.
Is New Castle County one of the largest cities in United States?
With a population of 570,719, New Castle County is one of the notable urban areas in United States. It ranks #122 out of 867 cities in the country.
