Like the rest of the region, Gladwyne, known until 1891 as "Merion Square", originally was settled by Welsh Quakers beginning in 1682. It was given its new name to lessen confusion with the many "Merions" in the area, including the town of Merion, Lower Merion Township, and Upper Merion Township, and in imitation of the Welsh names of adjoining towns, although its new name was meaningless in Welsh. Twenty-four mills operated along Mill Creek through the beginning of the twentieth century, and the major road through residential Gladwyne runs along the banks of the creek. After the American Civil War and following construction of the Pennsylvania Railroad's Main Line west from Center City, wealthy Philadelphians located many of their summer homes there.