Greencastle is a very small borough located in the state of Pennsylvania. With a population of 4,224 people and three associated neighborhoods, Greencastle is the 360th largest community in Pennsylvania.

Also of interest is that Greencastle has more people living here who work in computers and math than 95% of the places in the US.

A relatively large number of people in Greencastle telecommute to their jobs. Overall, about 9.63% of the workforce works from home. While this may seem like a small number, as a fraction of the total workforce it ranks among the highest in the country. These workers are often telecommuters who work in knowledge-based, white-collar professions. For example, Silicon Valley has large numbers of people who telecommute. Other at-home workers may be self-employed people who operate small businesses out of their homes.

Being a small borough, Greencastle does not have a public transit system used by locals to get to and from work.

The overall education level of Greencastle citizens is substantially higher than the typical US community, as 29.46% of adults in Greencastle have at least a bachelor's degree, and the average American community has 21.84%.

The per capita income in Greencastle in 2022 was $44,613, which is wealthy relative to Pennsylvania and the nation. This equates to an annual income of $178,452 for a family of four. However, Greencastle contains both very wealthy and poor people as well.

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

The most common language spoken in Greencastle is English. Other important languages spoken here include Spanish and Arabic.