Aldan is a borough in Delaware County, Pennsylvania, United States. The population was 4,313 at the 2000 census.
According to the United States Census Bureau, the borough has a total area of 0.6 square miles (1.6 km2), all of it land.
As of the census of 2000, there were 4,313 people, 1,751 households, and 1,157 families residing in the borough. The population density was 7,235.4 people per square mile (2,775.4/km²). There were 1,817 housing units at an average density of 3,048.1 per square mile (1,169.2/km²). The racial makeup of the borough was 93.30% White, 4.34% African American, 0.19% Native American, 1.34% Asian, 0.12% from other races, and 0.72% from two or more races. Hispanic or Latino of any race were 0.93% of the population.