The French explorer La Salle reportedly reached the Ohio River in 1669, but there was no significant interest in the valley until the French and the British began to struggle for control of the river in the 1750s. An early settlement was established at the forks of the Ohio (modern Pittsburgh) by the Ohio Company of Virginia in 1749, but it was captured by the French in 1754, and the unfinished Fort Prince George was renamed Fort Duquesne; it was recaptured by the British and renamed Fort Pitt in 1758. At the end of the French and Indian Wars, Britain gained control of the river by the treaty of 1763, but settlement of the area was prohibited. Britain ceded the region to the United States at the end of the Revolutionary War (1783), and it was opened to settlement by the Ordinance of 1787, which established the Northwest Territory.
Until the opening of the Erie Canal in 1825, the Ohio River was the main route to the newly opened West and the principal means of market transportation of the region's growing farm output. Traffic declined on the river after the railroads were built in the mid-1800s, although it revived after World War II. Comparatively little traffic remains on the Ohio, despite the new locks, dams, and channel improvements, which were all meant to spur economic activity on the river.
More on Ohio History from Infoplease:
See more Encyclopedia articles on: U.S. Physical Geography