The Susquehanna long served as a north-south transportation corridor but hindered east-west travel, leading ferries to appear along the river as early as the seventeenth century. In 1730, the Quaker John Wright began operating a ferry in this area. During the Revolutionary War, with British troops occupying Philadelphia in late 1777, the Continental Congress retreated westward, crossed the Susquehanna on Wright's Ferry, and established a capital in nearby York City for nine months, while the river helped protect the fledgling American government from hostile British troops. In 1814, the first bridge connecting Wrightsville and Columbia was completed as the longest covered bridge in the world at 5,690 feet. Since then, five additional bridges have spanned the Susquehanna at this site; of the six, two were destroyed by natural forces, and one was burned in 1863 by Union militiamen and townspeople to prevent Confederate forces from invading Lancaster County and reaching Harrisburg. In the decades before the Civil War, the Susquehanna also served as a south-north escape route for fugitive slaves traveling the clandestine Underground Railroad in search of freedom.