Northumberland is a very small borough located in the state of Pennsylvania. With a population of 3,839 people and two associated neighborhoods, Northumberland is the 401st largest community in Pennsylvania.

The education level of Northumberland citizens, measured as those with bachelor's degrees or advanced degrees, is similar to the national average for all American cities and towns. 20.16% of adults 25 and older in Northumberland have a college degree.

The per capita income in Northumberland in 2022 was $31,096, which is lower middle income relative to Pennsylvania and the nation. This equates to an annual income of $124,384 for a family of four. However, Northumberland contains both very wealthy and poor people as well.

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

The most common language spoken in Northumberland is English. Other important languages spoken here include Polish and Italian.