Harpers Ferry National Historical Park is located at the confluence of the Potomac and Shenandoah rivers in the states of West Virginia, Virginia, and Maryland. George Washington, Thomas Jefferson, Meriwether Lewis, John Brown, Stonewall Jackson, and Frederick Douglass are just a few of the prominent individuals who left their mark on this place. Harpers Ferry witnessed the first successful application of interchangeable manufacture, the arrival of the first successful American railroad, John Brown's attack on slavery, the largest surrender of Federal troops during the Civil War, and the education of former slaves in one of the earliest integrated schools in the United States. Leashed pets are permitted in the park, but are not allowed in the buildings. Leashes must be no longer than six feet.