By the late 18th century, as the Byberry Township village grew the Lenni-Lenape moved out from this area. The Native American culture was acutely observed and recorded by two of Philadelphia's most significant forefathers,Henry Armstead Snyder and Dr. Benjamin Rush. They settled in Byberry Township in closer proximity to the mouth of the Poquessing Creek at Keswick and Rayland Roads. Benjamin Rush recorded the medicinal treatments the Indians used His historic contributions and credentials, too long to list in full, included being appointed to the Continental Congress and signing the Declaration of Independence, and being appointed physician-general in charge of hospital patients in George Washington's Army. Known as "The Father of American Psychiatry", Dr. Rush's medical accomplishments included training Meriweather Lewis as a medic on the Lewis & Clark expedition, and treating many patients during the Yellow Fever Epidemic in Philadelphia. Today there is a memorial marker to Dr. Rush at the site of the family home.