Flagtown is an unincorporated community and census-designated place located within Hillsborough Township, in Somerset County, in the U.S. state of New Jersey.
As of the 2020 census, Flagtown had a population of 1,070.
History
In 1850 prior to any railroads coming through the area a Somerset County map refers to the area as Flaggtown. Later in 1873 the South Branch Railroad cut through the area just north of the present Lehigh Valley Railroad line and the Easton and Amboy Railroad was built (currently the Lehigh Valley Railroad line that is still active). The area to the north of the railroads was referred to as Flaggtown Station while the area to the south maintained the name Flaggtown. At this point only one train station was marked on the map west of South Branch road between the two rail lines. Finally by 1891 Flaggtown Station is no longer indicated on any maps and Flaggtown is consistently printed as Flagtown on maps. By 1891 two train stations are indicated on USGS maps, one for each line, both just west of South Branch Road. No remains of either station exist today. The name change was initiated by the US Post Office dealing with the confusion of having a Flaggtown next to Flaggtown Station. On January 28th 1878 Flaggtown was renamed Frankfort and Flagtown Station became Flagtown. It's not clear why the "g" was dropped.
The name Flagtown was a corruption of the original Flaggtown. The original Flaggtown (later renamed Frankfort, when Flagtown Station became Flagtown) was named for Jacob Flagg, who purchased a tract in 1700. Some years later, J. Flagg, a descendant and proprietor of a local tavern had it used as headquarters for the Hillsborough Company in the American Revolutionary War. At election time, the tavern served as a voting place. The first school was built there about 1725 on a knoll near the future site of the railroad station and it is said that William Parrish taught there. When the building was replaced in 1795, it was painted red and white and called "The Old Red School House."