[5] The community of Stewartsville was named after Thomas Stewart, a secretary to George Washington, who purchased property in the area in 1793.

[14] According to the United States Census Bureau, the CDP had a total area of 0.129 square miles (0.333 km2), all of which was land.

[6][2] The 2010 United States census counted 349 people, 134 households, and 96 families in the CDP.

[13] As of the 2000 United States Census, the population for ZIP Code Tabulation Area 08886 was 4,854.

Stewartsville had a station on the Morris and Essex Railroad, located 80 miles (130 km) from New York City.