The community is nestled within the heart of the Raritan Valley region, with the Manalapan Brook and Matchaponix Brook forming the confluence of the South River (a Raritan River tributary) inside the borough.

[25] The Bordentown and South Amboy Turnpike, a stagecoach route built in 1816, passed through Spotswood.

[25] The Camden and Amboy Railroad, chartered in 1830, followed this stagecoach route and reached Spotswood in 1832.

[27] Spotswood was incorporated as a borough by an act of the New Jersey Legislature on April 15, 1908, from portions of East Brunswick Township, based on the passage of a referendum held on May 12, 1908.

[31][32][33] The 2010 United States census counted 8,257 people, 3,128 households, and 2,143 families in the borough.

[40] As of the 2000 United States census[16] there were 7,880 people, 3,099 households, and 2,163 families residing in the borough.

The racial makeup of the borough was 99.24% White, 0.05% African American, 0.5% Asian, 0.01% Pacific Islander, and 0.20% from two or more races.

[43] The governing body is comprised of the mayor and the five-member borough council, who are chosen at-large to four-year terms of office on a non-partisan basis in elections held on a staggered basis in even-numbered years as part of the November general election.

[45] As of 2024[update], the Mayor of Spotswood is Jackie Palmer, whose term of office ends December 31, 2024.

[3] Members of the Borough Council are Council President Nicholas Legakis (2026), William Lawrence "Larry" Kraemer (2026), Edward Lesko (2024), Dawn Schwartz (2026) and Andrew Zaborney (2024; elected to serve an unexpired term).

[46][47][48][49] In the 2022 borough elections, Kraemer retained his seat, while Legakis and Schwartz joined the council to replace outgoing councilmembers Theodore Ricci (2022) and Charles Spicuzzo (2022).

[50][49] In August 2022, Andrew Zaborney was sworn in to fill the seat expiring in December 2024 that had been held by Marilyn Israel until she resigned from office.

[54] Citing potential savings of $25,000, Spotswood's council approved a measure in 2010 that would allow the borough to take advantage of new state legislation under which it would to shift its non-partisan municipal elections from May to the November general election, with the first municipal race taking place in November 2012.

[55] In the November 2012 general election, Nicholas Poliseno defeated Curtis Stollen in the mayoral race to succeed Thomas W. Barlow, who didn't run for re-election.

Council incumbents Frank LoSacco and Edward T. Seely ran unopposed.

[62] For the 119th United States Congress, New Jersey's 12th congressional district is represented by Bonnie Watson Coleman (D, Ewing Township).

[65] For the 2024-2025 session, the 12th legislative district of the New Jersey Legislature is represented in the State Senate by Owen Henry (R, Old Bridge Township) and in the General Assembly by Robert D. Clifton (R, Matawan) and Alex Sauickie (R, Jackson Township).

[67] As of 2025[update], Middlesex County's Commissioners (with party affiliation, term-end year, and residence listed in parentheses) are: Director Ronald G. Rios (D, Carteret, 2027),[68] Deputy Director Shanti Narra (D, North Brunswick, 2027),[69] Claribel A.

[101] The Spotswood Public Schools serve students in pre-kindergarten through twelfth grade.

[120] The main roads that pass through Spotswood include Middlesex County Route 613 (Devoe Avenue / Main Street / Summerhill Road) connecting Monroe Township to the south and East Brunswick Township to the north[121] and Middlesex County Route 615 (Manalapan Road / Main Street) connecting Helmetta in the southwest to East Brunswick Township in the borough's northwest corner.