The Great River Road in Illinois follows the Mississippi River through the nation’s heartland, bringing together the history and heritage of the Mississippi River and Middle America with river cultures, natural areas, wildlife, agriculture, and outdoor recreation along its 550-mile route. Along the road are prehistoric Native American cities, forts that secured the river during three wars, several National Historic Districts, and regional sites including Cahokia Mounds, Fort de Chartes, the Pierre Menard home, Horseshoe Lake, and vineyards, orchards, and farmers' markets. At the confluence of the Mississippi and Ohio Rivers, Cairo grew in the mid 1880s into an active steamboat port, commercial center, and river town that drew bankers, developers, merchants, shipping magnates, and steamship pilots; its Washington Avenue was once known as Millionaire's Row, and landmarks such as Magnolia Manor, Riverlore, the Alfred B. Safford Library, the Cairo Customs House and Museum, and the Cairo Historic District reflect the architectural diversity brought by the rivers. The confluence also held major strategic importance during the American Civil War, when Camp Defiance, now Fort Defiance, served as a staging area for Union troops in the Western Campaign, gunboats based there helped control the waterways, Union ironclads were built six miles up the Ohio River, and Cairo's harbor supplied the campaign with soldiers and supplies. Among those connected with this history are John A. Logan, who fought in eight major campaigns and later commanded all Union forces in the Atlanta Campaign, Ulysses S. Grant, who arrived at Camp Defiance in 1861 and took command of the Western Campaign, and Mary Bickerdyke, who cared for wounded soldiers in at least 19 battles and improved conditions in Union hospitals.