New Castle is a city located in Delaware. With a 2020 population of 5,493, it is the 10th largest city in Delaware and the 4500th largest city in the United States. New Castle is currently declining at a rate of -0.33% annually but its population has increased by 3.94% since the most recent census, which recorded a population of 5,285 in 2010. New Castle reached it's highest population of 5,529 in 2018. Spanning over 3 miles, New Castle has a population density of 1,629 people per square mile.
The average household income in New Castle is $86,047 with a poverty rate of 6.52%. The median rental costs in recent years comes to $1,206 per month, and the median house value is $195,400. The median age in New Castle is 49.5 years, 46.2 years for males, and 51.7 years for females. For every 100 females there are 97.2 males.