[19] The township was named for James Alexander, a surveyor who served as New Jersey Attorney General and who had acquired 10,000 acres (4,000 ha) of land in the area in 1744.

[1][2] Unincorporated communities, localities and place names located partially or completely within the township include Everittstown, Little York, Mechlings Corner, Mount Pleasant, Mount Salem, Palmyra and Swinesburg.

[24][25][26] The 2010 United States census counted 4,938 people, 1,758 households, and 1,384 families in the township.

[38] As of the 2000 United States census[13] there were 4,698 people, 1,535 households, and 1,290 families residing in the township.

In the November 2020 general election, voters approved a ballot question that asked if they wanted to expand the township committee from three members to five.

[3][44][21][45][46][47][43] In September 2015, the Township Committee selected Michelle Garay from three candidates nominated by the Republican municipal committee to fill the vacant seat expiring in December 2016 that had been held by Harry Swift until his death in office earlier that month.

[48][49][50] Christian Pfefferle took office in November 2014 after running unopposed to fill the 14 months remaining in the term of the seat that had been vacated by Gabe Plummer when he resigned after he had moved outside of the township in January 2014; Curtis Schick had filled the seat on an interim basis.

[53][54][55] For the 119th United States Congress, New Jersey's 7th congressional district is represented by Thomas Kean Jr. (R, Westfield).

[57] 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 elected on a countywide basis are Clerk Mary H. Melfi (R; Flemington, 2026),[66][67] Sheriff Fredrick W. Brown (R; Alexandria Township, 2025)[68][69] and Surrogate Heidi Rohrbach (R; Lebanon Township, 2028).

[70][71] Like most municipalities in Hunterdon County, the township leans very strongly towards the Republican Party on the national and state levels.

[80] The Alexandria Township School District serves students in pre-kindergarten through eighth grade.

[85] Students in public school for ninth through twelfth grades attend Delaware Valley Regional High School, together with students from Frenchtown, Holland Township, Kingwood Township and Milford.

[91] The Alexandria Township Education Foundation, is a non-profit organization established in 1997, whose mission is to help achieve and maintain an extra margin of excellence by employing private resources to supplement traditional school district funding.

[92] 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.