Altoona (ăltōˈnə) [key], industrial city (1990 pop. 51,881), Blair co., central Pa., on the eastern slopes of the Allegheny Mts., near the source of the Juniata River; settled c.1769, laid out (1849) by the Pennsylvania RR as a switching point for locomotives preparing to mount the Allegheny Plateau; inc. as a city 1868. It is a railroad center with construction and repair shops. Manufactures include fabricated metal products, food, machinery, electrical equipment, and chemicals. Nearby tourist attractions are the Horseshoe Curve constructed by the Pennsylvania RR, a world-famous engineering feat; and Wopsononock Mt. (2,580 ft/786 m high). A branch of Pennsylvania State Univ. is in Altoona.