Falls of the Ohio in the context of "U.S. Army Corps of Engineers"

The Ohio River (Seneca: Ohi:yo') is a 981-mile-long (1,579 km) river in the United States. It is located at the boundary of the Midwestern and Southern United States, flowing in a southwesterly direction from Pittsburgh, Pennsylvania, to its mouth on the Mississippi River in Cairo, Illinois. It is the third largest river by discharge volume in the United States and the largest tributary by volume of the Mississippi River. It is also the sixth oldest river on the North American continent. The river flows through or along the border of six states, and its drainage basin includes parts of 14 states. Through its largest tributary, the Tennessee River, the basin includes several states of the southeastern United States. It is the source of drinking water for five million people.

The river became a primary transportation route for pioneers during the westward expansion of the early U.S. The lower Ohio River just below Louisville was obstructed by rapids known as the Falls of the Ohio where the elevation falls 26 feet (7.9 m) in 2 miles (3.2 km) restricting larger commercial navigation, although in the 18th and early 19th century its three deepest channels could be traversed by a wide variety of craft then in use. In 1830, the Louisville and Portland Canal (now the McAlpine Locks and Dam) bypassed the rapids, allowing even larger commercial and modern navigation from the Forks of the Ohio at Pittsburgh to the Port of New Orleans at the mouth of the Mississippi on the Gulf of Mexico. Since the "canalization" of the river in 1929, the Ohio has not been a natural free-flowing river; today, it is divided into 21 discrete pools or reservoirs by 20 locks and dams for navigation and power generation.

The Louisville and Portland Canal was a 1.9-mile (3.1 km) canal bypassing the Falls of the Ohio River at Louisville, Kentucky. The Falls form the only barrier to navigation between the origin of the Ohio at Pittsburgh and the port of New Orleans near the Gulf of Mexico; circumventing them was long a goal for Pennsylvanian and Cincinnatian merchants. The canal opened in 1830 as the private Louisville and Portland Canal Company but was gradually bought out during the 19th century by the federal government, which had invested heavily in its construction, maintenance, and improvement.

The Louisville and Portland Canal was renamed as the McAlpine Locks and Dam in 1962 after extensive modernization. The name "Louisville and Portland Canal" (or simply "Portland Canal") is still used to refer to the canal itself, which runs between the Kentucky bank and Shippingport Island from about 10th Street down to the locks at 27th Street.

The McAlpine Locks and Dam are a set of locks and a hydroelectric dam at the Falls of the Ohio River at Louisville, Kentucky. They are located at mile point 606.8, and control a 72.9-mile-long (117.3 km) navigation pool. The locks and their associated canal were the first major engineering project on the Ohio River, completed in 1830 as the 1.9-mile Louisville and Portland Canal, designed to allow shipping traffic to navigate through the Falls of the Ohio. The locks system is operated by the U.S. Army Corps of Engineers.

At present, the normal pool elevation is 420 feet (130 m) above sea level and the drainage area above the dam is 91,170 square miles (236,100 km). The average daily flow at McAlpine is 118,000 cubic feet per second (3,340 m/s). The lock chambers are located at the dam on the Kentucky side of the Ohio River and are capable of a normal lift of 37 feet (11 m) between the McAlpine pool upstream and the Cannelton pool downstream.

The Wilderness Road was one of two principal routes used by colonial and early national era settlers to reach Kentucky from the East. Although this road goes through the Cumberland Gap into southern Kentucky and northern Tennessee, the other (more northern route) is sometimes called the "Cumberland Road" because it started in Fort Cumberland in Maryland. Despite Kentucky Senator Henry Clay's advocacy of this route early in the 19th century, the northern route was selected for the National Road, connecting near Washington, Pennsylvania into the Ohio Valley of northern Kentucky and Ohio.

In 1775, Daniel Boone blazed a trail for the Transylvania Company from Fort Chiswell in Virginia through the Cumberland Gap. It was later lengthened, following Indian trails, to reach the Falls of the Ohio at Louisville. The Wilderness Road was steep, rough and narrow. It could be traversed only on foot or horseback. By contrast, wagons could travel along the National Road route (originally the Braddock Road blazed by the competing Ohio Company and George Washington circa 1750), particularly after the improvements.