Part of the township is on the Hunterdon Plateau, while the southern portions are in the Amwell Valley.

The Township adjoins the Delaware River on the southwestern portion of Hunterdon County, which provides its name.

Sergeantsville is at the township's center and includes the municipal building, local public school and Post Office.

A "Thanksgiving in the Country" offers a tour of notable homes in Sergeantsville, which raises funds for the Facial Reconstruction Unit of the Children's Hospital of Philadelphia.

[23] Historian and cartographer John P. Snyder has erroneously stated that a referendum was held on that date, but there was in fact no referendum and the people of Amwell knew nothing about the division until after the Legislature passed the bill.

[1][2] Unincorporated communities, localities and place names located partially or completely within the township include Bowne,[citation needed] Brookville, Dilts Corner, Grover, Headquarters, Locktown, Prallsville, Raven Rock, Rosemont, Sand Brook, Sandy Ridge and Sergeantsville.

[26][27][28] The 2010 United States census counted 4,563 people, 1,788 households, and 1,348 families in the township.

Of all households, 19.0% were made up of individuals and 7.7% had someone living alone who was 65 years of age or older.

[40] As of the 2000 United States census[15] there were 4,478 people, 1,643 households, and 1,302 families residing in the township.

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

[51] For the 2024-2025 session, the 15th legislative district of the New Jersey Legislature is represented in the State Senate by Shirley Turner (D, Lawrence Township) and in the General Assembly by Verlina Reynolds-Jackson (D, Trenton) and Anthony Verrelli (D, Hopewell Township).

[58][59] Constitutional officers elected on a countywide basis are Clerk Mary H. Melfi (R; Flemington, 2026),[60][61] Sheriff Fredrick W. Brown (R; Alexandria Township, 2025)[62][63] and Surrogate Heidi Rohrbach (R; Lebanon Township, 2028).

[77] The school is located on a site covering 26 acres (11 ha) adjacent to the community of Sergeantsville and 3 miles (4.8 km) from the Delaware River.

[80] Seats on the high school district's nine-member board of education are allocated based in the population of the five constituent municipalities who participate in the school district, with one seat allocated to Delaware Township.

[81] 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.

People who were born in, residents of, or otherwise closely associated with Delaware Township include: