Plainfield Township is a township located in Northampton County, Pennsylvania. As of the 2000 census, the township had a total population of 5,668.
According to the United States Census Bureau, the township has a total area of 64.2 km˛ (24.8 mi˛). 64.1 km˛ (24.7 mi˛) of it is land and 0.1 km˛ (0.04 mi˛) of it is water. The total area is 0.16% water.
As of the census2 of 2000, there are 5,668 people, 2,130 households, and 1,637 families residing in the township. The population density is 88.5/km˛ (229.2/mi˛). There are 2,191 housing units at an average density of 34.2/km˛ (88.6/mi˛). The racial makeup of the township is 98.85% White, 0.37% African American, 0.02% Native American, 0.28% Asian, 0.00% Pacific Islander, 0.14% from other races, and 0.34% from two or more races. 0.67% of the population are Hispanic or Latino of any race.
There are 2,130 households out of which 30.4% have children under the age of 18 living with them, 68.0% are married couples living together, 5.6% have a female householder with no husband present, and 23.1% are non-families. 18.6% of all households are made up of individuals and 9.0% have someone living alone who is 65 years of age or older. The average household size is 2.62 and the average family size is 3.00.
In the township the population is spread out with 22.2% under the age of 18, 6.1% from 18 to 24, 27.1% from 25 to 44, 27.8% from 45 to 64, and 16.7% who are 65 years of age or older. The median age is 42 years. For every 100 females there are 96.9 males. For every 100 females age 18 and over, there are 93.2 males.
The median income for a household in the township is $49,019, and the median income for a family is $54,856. Males have a median income of $39,334 versus $25,145 for females. The per capita income for the township is $20,639. 3.7% of the population and 1.7% of families are below the poverty line. Out of the total population, 2.9% of those under the age of 18 and 4.9% of those 65 and older are living below the poverty line.