Lansdowne is a borough in Delaware County, Pennsylvania, United States located 6 miles southwest of the center of Philadelphia. It was named for the Marquess of Lansdowne. As of the 2010 census the borough had a population of 10,620.Lansdowne grew quickly in the early part of the twentieth century when a railroad stop was established near the intersection of Lansdowne Avenue and Baltimore Pike. The borough is primarily residential with a commercial center near the original railroad stop. The borough also contained some light industrial buildings which have been in decline in recent decades.The borough is sometimes erroneously spelled "Landsdowne" or confused with Lansdale, in nearby Montgomery County.