Heidelberg Township, Lehigh County, Pennsylvania
A farm in Heidelberg Township
|Elevation||797 ft (242.9 m)|
|Area||24.7 sq mi (64 km2)|
|- land||24.7 sq mi (64 km2)|
|- water||0.0 sq mi (0 km2), 0%|
|Density||132.7 / sq mi (51.2 / km2)|
|- summer (DST)||EDT (UTC-4)|
The population of Heidelberg Township was 3,279 at the 2000 census.
According to the United States Census Bureau, the township has a total area of 24.7 square miles (64 km2), all of it land. Blue Mountain separates it from Carbon County and the township's portion contains Lehigh County's highest point, Bake Oven Knob at 1,585 feet. Its villages include Diebertsville, Germans Corners, Germansville (both pronounced with a hard "g",) Jordan Valley, Lochland (also in Lynn Township,) Pleasant Corners, and Saegersville. Its numbered routes are 100 and 309 and 100's northern terminus on 309 is in Pleasant Corners.
Heidelberg Township is located in the Delaware watershed. Almost all of it is drained into the Lehigh River (mainly by the Jordan Creek which starts in Heidelberg,) except for a very small area in the southwest portion that is drained by the Maiden Creek into the Schuylkill River.
Adjacent municipalities 
- Washington Township (east)
- North Whitehall Township (southeast)
- Lowhill Township (south)
- Weisenberg Township (tangent to the southwest)
- Lynn Township (west)
- West Penn Township, Schuylkill County (tangent to the northwest)
- East Penn Township, Carbon County (north)
As of the census of 2000, there were 3,279 people, 1,187 households, and 943 families residing in the township. The population density was 132.7 people per square mile (51.3/km²). There were 1,234 housing units at an average density of 50.0/sq mi (19.3/km²). The racial makeup of the township was 98.69% White, 0.27% African American, 0.06% Native American, 0.30% Asian, 0.21% from other races, and 0.46% from two or more races. Hispanic or Latino of any race were 0.88% of the population.
There were 1,187 households out of which 38.6% had children under the age of 18 living with them, 67.9% were married couples living together, 7.6% had a female householder with no husband present, and 20.5% were non-families. 15.2% of all households were made up of individuals and 4.9% had someone living alone who was 65 years of age or older. The average household size was 2.76 and the average family size was 3.08.
In the township the population was spread out with 26.5% under the age of 18, 6.5% from 18 to 24, 32.0% from 25 to 44, 26.4% from 45 to 64, and 8.7% who were 65 years of age or older. The median age was 37 years. For every 100 females there were 104.0 males. For every 100 females age 18 and over, there were 99.9 males.
The median income for a household in the township was $55,030, and the median income for a family was $57,019. Males had a median income of $40,062 versus $29,205 for females. The per capita income for the township was $23,521. About 7.0% of families and 6.5% of the population were below the poverty line, including 6.2% of those under age 18 and 6.9% of those age 65 or over.
Public education 
The Township is served by the Northwestern Lehigh School District.