Lansdale is a borough in Montgomery County, Pennsylvania, United States. It is a densely-populated commuter town, with many residents traveling daily to Philadelphia using SEPTA Regional Rail's Lansdale/Doylestown Line. In the year 1900, 2,754 people lived here; in 1910, 3,551; and in 1940, 9,316 people were inhabitants of Lansdale. The population was 18,773 at the 2020 census. Lansdale is the center of the North Penn Valley, a region which includes the surrounding townships and boroughs.