In general, the road climbed westwards along the Amerindian trail known as Chief Nemacolin's Path, once followed and improved by a young George Washington, then also followed by the Braddock Expedition. Using the Cumberland Narrows, its first phase of construction crossed the Allegheny Mountains entered southwestern Pennsylvania, reaching the Allegheny Plateau in Somerset County, Pennsylvania. There, travelers could turn off to Pittsburgh or continue west through Uniontown and reach navigable water, the Monongahela River, at Brownsville, Pennsylvania, which was by then a major outfitting center and riverboat-building emporium. Many settlers boarded boats there to travel down the Ohio and up the Missouri, or elsewhere on the Mississippi watershed.