Glen Gardner is a borough in Hunterdon County, New Jersey, United States. At the time of the 2010 United States Census, the borough's population was 1,704, reflecting a decline of 198 from the 1,902 counted in the 2000 Census, which had in turn increased by 237 from the 1,665 counted in the 1990 Census.Glen Gardner is located at the extreme western border of Lebanon Township and was incorporated as a borough by an act of the New Jersey Legislature on March 26, 1919, from portions of both Lebanon Township and Bethlehem Township based on the results of a referendum held that same day. Portions of the borough were ceded to Hampton borough in 1931.The area that is now Glen Gardner had been known as Eveland's Tavern for tavernkeeper John Eveland. Later, the area was variously called Spruce Run Mills and Sodom. The name of both the community and post office were officially changed to Glen Gardner in 1871 in honor of the Gardner brothers who owned a chair and frame factory in the area.