|South Middleton Township, Pennsylvania|
|— Township —|
Map of Cumberland County, Pennsylvania highlighting South Middleton Township
Map of Cumberland County, Pennsylvania
|- Type||Board of Supervisors|
|- Total||49.5 sq mi (128.2 km2)|
|- Density||261.6/sq mi (101/km2)|
|Time zone||Eastern (EST) (UTC-5)|
|- Summer (DST)||EDT (UTC-4)|
According to the United States Census Bureau, the township has a total area of 49.5 square miles (128.3 km²), of which 49.5 square miles (128.1 km²) is land and 0.1 square miles (0.1 km²) (0.10%) is water.
As of the census of 2000, there were 12,939 people, 5,081 households, and 3,805 families residing in the township. The population density was 261.6 people per square mile (101.0/km²). There were 5,302 housing units at an average density of 107.2/sq mi (41.4/km²). The racial makeup of the township was 97.16% White, 0.67% African American, 0.07% Native American, 0.94% Asian, 0.09% Pacific Islander, 0.33% from other races, and 0.74% from two or more races. Hispanic or Latino of any race were 0.90% of the population.
There were 5,081 households out of which 31.1% had children under the age of 18 living with them, 64.7% were married couples living together, 7.8% had a female householder with no husband present, and 25.1% were non-families. 21.0% of all households were made up of individuals and 9.9% had someone living alone who was 65 years of age or older. The average household size was 2.51 and the average family size was 2.91.
In the township the population was spread out with 23.8% under the age of 18, 5.6% from 18 to 24, 27.4% from 25 to 44, 26.2% from 45 to 64, and 17.0% who were 65 years of age or older. The median age was 41 years. For every 100 females there were 94.7 males. For every 100 females age 18 and over, there were 91.6 males.
The median income for a household in the township was $50,503, and the median income for a family was $60,511. Males had a median income of $40,427 versus $26,593 for females. The per capita income for the township was $24,370. About 3.4% of families and 4.4% of the population were below the poverty line, including 4.8% of those under age 18 and 7.9% of those age 65 or over.