a city, capital of Montgomery county, state of Ohio, N. America, situated at the confluence of the Mad and Miami rivers, 66 miles W.S.W. of Columbus. It is a place of quite recent date. In the beginning of 1829 the Miami Canal, between Cincinnati and Dayton, 60 miles in length, was completed,—and from that date the prosperity of the town commenced. Pop. (1850) 10,977. Dayton is connected by railway with Cincinnati, Toledo, Xenia, &c. A canal from the Mad river, four miles above the town, furnishes an important motive power to manufacturers and others. It has extensive manufactures of railway carriages, stoves, paper, linseed oil, and oilcake. There are two market-houses, and an elegant court-house.