[20] The township is located within the heart of the Amwell Valley and Raritan Valley regions, as the South Branch of the Raritan River (along with the Neshanic River) flows through the center of the township.

Flemington was formed within the township on March 14, 1870, and became an independent borough on April 7, 1910.

[21] The township's name is derived from the Raritan tribe, a Native American band of Lenape people that inhabited Central New Jersey.

[26][27][28] Unincorporated communities, localities and place names located partially or completely within the township include: Cloverhill, Copper Hill, Croton, Flemington Junction, Klinesville, Larisons Corners, Muirhead, Reaville,[29] as well as Bartles Corners,[citation needed] Gary Corner,[citation needed] Mount Carmel, Rockefellows Mills,[citation needed] Thachers Hill[citation needed] and Voorhees Corner.

The 2010 United States census counted 22,185 people, 8,056 households, and 6,058 families in the township.

Of all households, 20.7% were made up of individuals and 8.7% had someone living alone who was 65 years of age or older.

[43] As of the 2000 United States census[15] there were 19,809 people, 6,939 households, and 5,391 families residing in the township.

[3][47][48][49][50][51] In June 2022, Jeff Kuhl resigned from the seat he had held expiring in December 2024 in order to fill a vacant seat on the Hunterdon County Board of County Commissioners.

[52] The Township Committee appointed Bob King to fill Kuhl's vacant committee seat; King will serve on an interim basis until the November 2022 general election, when voters will choose a candidate to serve the balance of the term of office.

[55][56][57] Prior to the 2010 Census, Raritan Township had been part of the 11th Congressional District, a change made by the New Jersey Redistricting Commission that took effect in January 2013, based on the results of the November 2012 general elections.

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

[60] For the 2024-2025 session, the 16th legislative district of the New Jersey Legislature is represented in the New Jersey Senate by Andrew Zwicker (D, South Brunswick) and in the General Assembly by Mitchelle Drulis (D, East Amwell Township) and Roy Freiman (D, Hillsborough Township).

[67][68] Constitutional officers elected on a countywide basis are Clerk Mary H. Melfi (R; Flemington, 2026),[69][70] Sheriff Fredrick W. Brown (R; Alexandria Township, 2025)[71][72] and Surrogate Heidi Rohrbach (R; Lebanon Township, 2028).

[94][95][96][97] Raritan Township is allocated seven of the nine seats on the regional district's board of education.

[102][103] Eighth grade students from all of Hunterdon County are eligible to apply to attend the high school programs offered by the Hunterdon County Vocational School District, a county-wide vocational school district that offers career and technical education at its campuses in Raritan Township and at programs sited at local high schools, with no tuition charged to students for attendance.

[114] The Norfolk Southern Railway's Lehigh Line (formerly the mainline of the Lehigh Valley Railroad), runs through most of the northeast part of Raritan Township close to its northeast boundary.

[115] On December 14, 1776, during the American Revolutionary War, local militia led by Captain John Schenck ambushed a party of British dragoons returning from a raid on Flemington.

[116] On December 14, 1976, as part of the United States Bicentennial, Raritan Township dedicated a monument to the Amwell Militia at the site along US 202 and Route 31 northbound.

[117] A memorial monument to Geary is located nearby along with a historical information plaque describing the Amwell Skirmish.