Ralpho Township is a municipality located in Northumberland County, Pennsylvania. As of the 2000 census, the township population was 3,764.
According to the US Census Bureau, the township has a total area of 18.5 square miles, none of which is covered with water.
As of the census of 2000, there were 3,764 people, 1,497 households, and 1,121 families residing in the township. The population density was 203.9 people per square mile (78.7/km²). There were 1,600 housing units at an average density of 86.7/sq mi (33.5/km²). The racial makeup of the township was 99.31% White, 0.08% African-American, 0.08% Native American, 0.27% Asian, and 0.27% from two or more races. Hispanic or Latino of any race were 0.43% of the population.
There were 1,497 households out of which 31.9% had children under the age of 18 living with them, 65.7% were married couples living together, 6.9% had a female householder with no husband present, and 25.1% were non-families. 22.9% of all households were made up of individuals and 12.4% had someone living alone who was 65 years of age or older. The average household size was 2.47 and the average family size was 2.90.
In the township the population was spread out with 23.0% under the age of 18, 4.9% from 18 to 24, 25.3% from 25 to 44, 27.5% from 45 to 64, and 19.3% who were 65 years of age or older. The median age was 43 years. For every 100 females there were 95.1 males. For every 100 females age 18 and over, there were 90.7 males.
The median income for a household in the township was $44,318, and the median income for a family was $52,853. Males had a median income of $40,765 versus $24,179 for females. The per capita income for the township was $20,449. About 3.0% of families and 6.4% of the population were below the poverty line, including 7.9% of those under age 18 and 9.4% of those age 65 or over.