Willoughby Run is a tributary of Marsh Creek in Adams County, Pennsylvania in the United States. Willoughby Run flows southward between Herr Ridge and McPherson Ridge through the Gettysburg Battlefield. In popular culture This article was a topic of conversation in the third episode of series one of the web series "Two Of These People Are Lying" hosted by The Technical Difficulties. References External links List of rivers of Pennsylvania Gettysburg Battlefield Tributaries of the Monocacy River Rivers of Adams County, Pennsylvania Rivers of Pennsylvania