Upper Darby Township is a township an largest municipality in Delaware County and the 5th largest municipality in the state of Pennsylvania. It was founded during a split from Darby Township on August 30, 1736. However it was not incorporated under the home rule charter until 1907. Located just 5.8 miles from Center City, and bordering the Philadelphia city limits via Cobbs Creek, many of its residents work in the city. The east-west Philadelphia subway (the 'El') terminates at 69th street, Upper Darby's principal business district. Several trolley and bus lines connect 69th Street Terminal to the western suburbs of Philadelphia. As of the 2000 census, the township had a total population of 81,821. By 2005, the population was estimated at 79,620.