Ardmore is an unincorporated community and census-designated place spanning the border between Delaware and Montgomery counties in the U.S. state of Pennsylvania. The population was 12,455 at the time of the 2010 census and had risen to 13,566 in the 2020 census. Ardmore is a suburb on the west side of Philadelphia within Lower Merion Township in Montgomery County and Haverford Township in Delaware County.