The name of both the community and post office were officially changed to Glen Gardner in 1871 to mark the glen of the Spruce Run and in honor of the Gardner brothers who owned a chair and frame factory in the area.

[22][23][24][25] As part of the 1931 settlement reached between the two municipalities to resolve a border dispute dating back to the borough of Glen Gardner's formation in 1919, Hampton paid Glen Gardner $4,000 (equivalent to $80,000 in 2023) for 20 acres (8.1 ha) of land that officially became part of the borough of Hampton.

[26] According to the United States Census Bureau, the borough had a total area of 1.55 square miles (4.01 km2), all of which was land.

[1][2] Bells Crossing and Clarksville are unincorporated communities located within Glen Gardner.

[27][28][29] The 2010 United States census counted 1,704 people, 768 households, and 434 families in the borough.

[35] At the 2000 United States census,[15] there were 1,902 people, 805 households and 474 families residing in the borough.

[6] The borough form of government used by Glen Gardner is a "weak mayor / strong council" government in which council members act as the legislative body with the mayor presiding at meetings and voting only in the event of a tie.

The mayor can veto ordinances subject to an override by a two-thirds majority vote of the council.

[37][38] This seven-member governing body enacts local ordinances, levies municipal taxes and conducts the affairs of the borough.

The mayor and borough council conducts all of its business during monthly meetings open to the public.

[39] As of 2023[update], the mayor of Glen Gardner is Republican Mattias E. Schroeter, whose term of office ends December 31, 2023.

[3][40][23][41][42][43][44][45] In April 2021, the borough council appointed Jason Hollenstein to fill the council seat expiring in December 2022 that had been held by Lisa Fielding until she resigned from office the previous month.

[43] James Ayotte was selected in May 2020 from a list of three names submitted by the Republican municipal committee to fill the seat expiring in December 2022 that had been held by Sandra Sutton-Lavis until she resigned from her seat in April.

[52][53][54] For the 119th United States Congress, New Jersey's 7th congressional district is represented by Thomas Kean Jr. (R, Westfield).

[56] For the 2024-2025 session, the 23rd legislative district of the New Jersey Legislature is represented in the State Senate by Doug Steinhardt (R, Lopatcong Township) and in the General Assembly by John DiMaio (R, Hackettstown) and Erik Peterson (R, Franklin Township).

[63][64] Constitutional officers elected on a countywide basis are Clerk Mary H. Melfi (R; Flemington, 2026),[65][66] Sheriff Fredrick W. Brown (R; Alexandria Township, 2025)[67][68] and Surrogate Heidi Rohrbach (R; Lebanon Township, 2028).

[85] Glen Gardner residents began to select which high school they wished to attend in 2014.