CORAOPOLIS, a borough of Allegheny county, Pennsyl vania, U.S.A., Iom. N.W. of Pittsburgh, on the west bank of the Ohio river, and served by the Pittsburgh and Lake Erie railroad. The population in 1930 was 10,724. It is in an oil and gas field, and has steel and iron foundries, glass works and factories making springs, nuts and bolts. The borough was incorporated in 1886.