Genesee, a river of western New York, rises in Potter co., Pa., within a few yards of the head waters of the Alleghany and the north branch of the Susquehanna, flows N. W. and N. E. through Alleghany, Wyoming, Livingston, and Monroe counties, N. Y., and falls into Lake Ontario 7 m. N. of Rochester. Its length is about 145 m. It is navigable from Lake Ontario to the N. line of Rochester. The mouth, protected by two fine piers, forms a good harbor, which gives rise to the village of Charlotte, on the W. side. The river abounds in beautiful scenery, especially in cataracts. In Livingston co., near Portage, are three falls within a distance of two miles, which are respectively 60, 90, and 110 ft. high; and for several miles below these the stream flows between perpendicular banks 400 ft. high. At the S. line of Rochester commences a series of rapids, which terminate in the centre of the city in a sheer fall of 9G ft., called Genesee falls. This was the scene of Sam Patch's last leap. Six miles from the mouth of the river is a broken fall of 84 ft., by which the stream reaches the level of the lake. The Genesee is tapped above the rapids to feed the Erie canal, which at Rochester crosses it by a fine limestone aqueduct of nine arches, each of 50 ft. span.

The Genesee Valley canal, commencing at Rochester, follows the course of the river for a considerable distance, locks into it at Mt. Morris, and crosses it at Portage by an aqueduct. The Buffalo branch of the Erie railway has a trestle bridge near the same place, 800 ft. long and 234 ft. high.