Weisenburg Township was formed out of the "Backparts of Macunjy" and part of the Allemangel, and was erected as a township in 1753. Weisenburg was named for the city Weissenburg, a fortress and town in Alsace, from the vicinity in which the majority of the townspeople had come. The first settlements took place in 1734, on and around the highlands in the vicinity of Ziegel Church. (Extracted from "Histories of the Counties of Lehigh and Carbon, In the Commonwealth of Pennsylvania," by Alfred Mathews, published in 1884.)
As of the census2 of 2000, there were 4,144 people, 1,458 households, and 1,214 families residing in the township. The population density was 59.7/km² (154.5/mi²). There were 1,514 housing units at an average density of 21.8/km² (56.5/mi²). The racial makeup of the township was 98.07% White, 0.53% African American, 0.02% Native American, 0.43% Asian, 0.29% from other races, and 0.65% from two or more races. Hispanic or Latino of any race were 1.25% of the population.
There were 1,458 households out of which 37.7% had children under the age of 18 living with them, 75.9% were married couples living together, 4.7% had a female householder with no husband present, and 16.7% were non-families. 11.8% of all households were made up of individuals and 3.8% had someone living alone who was 65 years of age or older. The average household size was 2.82 and the average family size was 3.09.
In the township the population was spread out with 25.9% under the age of 18, 5.7% from 18 to 24, 31.4% from 25 to 44, 27.6% from 45 to 64, and 9.3% who were 65 years of age or older. The median age was 39 years. For every 100 females there were 102.1 males. For every 100 females age 18 and over, there were 99.9 males.
The median income for a household in the township was $63,631, and the median income for a family was $70,852. Males had a median income of $45,898 versus $32,656 for females. The per capita income for the township was $27,163. About 1.8% of families and 2.3% of the population were below the poverty line, including 1.4% of those under age 18 and 4.5% of those age 65 or over.
The Township is served by the Northwestern Lehigh School District.