New Castle is a medium-sized city located in the state of Pennsylvania. With a population of 21,532 people and 16 associated neighborhoods, New Castle is the 37th largest community in Pennsylvania. New Castle has an unusually large stock of pre-World War II architecture, making it one of the older and more historic cities.

The citizens of New Castle are slightly less educated than the national average of 21.84% for the average city or town: 16.51% of adults in New Castle have a bachelor's degree or advanced degree

The per capita income in New Castle in 2022 was $22,196, which is low income relative to Pennsylvania and the nation. This equates to an annual income of $88,784 for a family of four. However, New Castle contains both very wealthy and poor people as well.

New Castle is a very ethnically-diverse city. The people who call New Castle home describe themselves as belonging to a variety of racial and ethnic groups. The greatest number of New Castle residents report their race to be White, followed by Black or African-American. Important ancestries of people in New Castle include Italian, German, Irish, Polish, and English.

The most common language spoken in New Castle is English. Other important languages spoken here include Spanish and Portuguese.