Marshallton is a census-designated place (CDP), located in Coal Township, in Northumberland County, Pennsylvania, United States.

[2] According to the United States Census Bureau, the CDP has a total area of 0.9 square miles (2.3 km2), all land.

As of the census[3] of 2000, there were 1,437 people, 640 households, and 384 families residing in the CDP.

There were 756 housing units at an average density of 866.1 per square mile (334.4/km2).

35.5% of all households were made up of individuals, and 20.3% had someone living alone who was 65 years of age or older.