In 1691 the Rittenhouse family opened a paper mill outside of Philadelphia and for the next forty years were the only paper manufacturers in America. Wilhelm Rittinghausen, later known as William Rittenhouse, was born in Mulheim, Germany and learned the paper making trade. He moved to Amsterdam at a young age and then emigrated to America with his three children in 1687. William's descendants continued to be active in the paper making business into the nineteenth century when the productivity of the mill gaveway to the new technology.