Bryn Mawr (pronounced brin-mahr; from Welsh for "big hill") is a census-designated place (CDP) in Lower Merion Township, Montgomery County, Pennsylvania, just west of Philadelphia along Lancaster Avenue (US-30) and the border with Delaware County. Bryn Mawr is located towards the center of what is known as the Main Line, a group of picturesque and affluent Philadelphia suburbs stretching from the city limits to Malvern. It is also home to Bryn Mawr College and as of the 2000 census, it had a population of 4,382. The name Bryn Mawr means "big hill" in Welsh and takes its name from an estate near Dolgellau in North Wales. This was the farm of Rowland Ellis, who emigrated to Pennsylvania from Dolgellau in 1686 to escape religious persecution.
Until 1869 and the coming of the Pennsylvania Railroad, the town was known as Humphreysville. The town was renamed by railroad agent William H. Wilson after he acquired on behalf of the railroad the 283 acres (1.15 km) that now comprise Bryn Mawr.