East Deer Township is a township in Allegheny County, Pennsylvania, United States. The population was 1,500 at the 2010 census.
According to the United States Census Bureau, the township has a total area of 2.6 square miles (6.7 km2), of which 2.3 square miles (6.0 km2) is land and 0.3 square miles (0.78 km2), or 11.83%, is water.
As of the census of 2000, there were 1,362 people, 606 households, and 350 families residing in the township. The population density was 590.3 people per square mile (227.6/km²). There were 682 housing units at an average density of 295.6/sq mi (114.0/km²). The racial makeup of the township was 96.84% White, 1.91% African American, 0.15% Asian, 0.07% from other races, and 1.03% from two or more races. Hispanic or Latino of any race were 0.07% of the population.
East Deer residents reported 19% being of German ancestry, 19% of Italian ancestry, 13% Irish ancestry, 11% Polish ancestry and 10% Slovak ancestry in 2000.
There were 606 households, out of which 23.4% had children under the age of 18 living with them, 41.4% were married couples living together, 12.0% had a female householder with no husband present, and 42.2% were non-families. 37.1% of all households were made up of individuals, and 16.5% had someone living alone who was 65 years of age or older. The average household size was 2.16 and the average family size was 2.82.
In the township the population was spread out, with 18.8% under the age of 18, 7.0% from 18 to 24, 32.5% from 25 to 44, 18.4% from 45 to 64, and 23.3% who were 65 years of age or older. The median age was 41 years. For every 100 females there were 81.8 males. For every 100 females age 18 and over, there were 77.2 males.