[22] Knowlton's name is variously attributed to Thomas Knowlton, a Colonel in the Continental Army during the American Revolutionary War who was killed in action at the Battle of Harlem Heights,[24] or to the knolls that characterize the area.

Within the township are several small hamlets, including Browning, Deckers Ferry, Mount Pleasant, Polkville, Ramseyburg, Warrington and Knowlton itself.

Columbia (with a 2010 Census population of 229[28]), Delaware (150[29]) and Hainesburg (91[30]) are unincorporated communities and census-designated places (CDPs) located within the township.

[31][32][33] Other unincorporated communities, localities and place names located partially or completely within the township include Browning, Deckers Ferry, Mount Pleasant, Polkville, Ramseyburg and Warrington.

[35][36] The Township's economic data (as is all of Warren County) is calculated by the US Census Bureau as part of the Allentown-Bethlehem-Easton, PA-NJ Metropolitan Statistical Area.

[48][49] The 2010 United States census counted 3,055 people, 1,097 households, and 864 families in the township.

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

[59] 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).

[64][65] Constitutional officers of Warren County are: Clerk Holly Mackey (R, Alpha; 2027),[66][67] Sheriff James McDonald Sr. (R, Phillipsburg; 2025)[68][69] and Surrogate Michael J. Doherty (R, Washington; 2025).

[73] Among the township's 2010 Census population, 65.7% (vs. 62.3% in Warren County) were registered to vote, including 85.7% of those ages 18 and over (vs. 81.5% countywide).

[89] Students from the township and from all of Warren County are eligible to attend Ridge and Valley Charter School in Frelinghuysen Township (for grades K–8, with Knowlton students among those given admission preference)[90] or Warren County Technical School in Washington borough (for 9–12),[91] with special education services provided by local districts supplemented throughout the county by the Warren County Special Services School District in Oxford Township (for PreK–12).

The field is located by Route 94 and is divided by the Lackawanna Cut-Off and is connected through an old tunnel (hence the name).

[93] Interstate 80 (Bergen-Passaic Expressway) is the main east–west limited access road, passing through the township for 7.24 miles (11.65 km) with a junction at Routes 94 and 46.

[95] U.S. Route 46 runs for 5.50 miles (8.85 km) through the township's southern portion.

[96] The Portland–Columbia Toll Bridge (part of Route 94), which is owned and operated by the Delaware River Joint Toll Bridge Commission, crosses the Delaware River and connects with Pennsylvania Route 611 in Portland, Pennsylvania.

The community of Columbia was also served by the NYS&W (Hainesburg also had a station), with the Lehigh and New England Railroad also passing through town.

In more recent years, development within Knowlton has been tied to the presence of U.S. Route 46 and, since the early 1970s, Interstate 80.

Many Knowlton residents use Route 80 to commute to their jobs either further east in New Jersey or further west in Pennsylvania.