The Great Falls of the Potomac River has figured prominently in the purposes of men since prehistoric time. Long before John Smith reached the falls in 1608, groups of Indians from East and West met at this great river barrier to trade and perform ceremonies in honor of the spirit of the "Roaring Waters." As early as 1754, George Washington visualized the Potomac River as an important avenue of trade and communication with the interior. Records show that, with the exception of Mount Vernon, Great Falls was perhaps as intimately associated with George Washington's everyday life as any other place in the country. As first President of the "Potomac Canal Company," Washington frequently visited the working parties as they constructed the canal and lock system which skirted the treacherous falls on the Virginia side. Matildaville, a town of about 16 hectares named after the wife of "Light Horse" Harry Lee and consisting of various dwellings, grist mill, market house, forge, sawmill, and tavern, sprang up along the banks of the canal. In 1802, the Patowmack Company canals were essentially completed, and hundreds of boats plied the river, bringing corn and wheat, coal and limestone, flaxseed, and furs downstream from the mountainous region around Cumberland. Many of the boats were sold for lumber in Georgetown, thus sparing the boatmen an arduous upstream journey. After the establishment of the Nation's Capital, Great Falls became a popular scenic attraction for residents and visitors alike. But Great Falls was not always as easily accessible as it is today. In 1845, a newspaper columnist, after praising the beauty and historic interest of the region, added, ..". the access to this interesting spot is, on both sides of the river, by the most infamous roads and the accommodations for visitors anything but what they ought to be " Visitors to Great Falls now number more than one-half million annually and, because of this continuing and mounting interest, the U.S. Geological Survey has joined with the National Park Service in preparing this booklet for better understanding and enjoyment of the Great Falls of the Potomac River. The original edition was published in 1970. The current edition has been revised and expanded to incorporate new information, an enlarged trail log, and changes in trail locations. Because the policy of the Geological Survey is to foster use of the International System of Units, all measurements in this edition are in the metric system.