Rockport is a city in Ohio Township and the county seat of Spencer County, Indiana, along the Ohio River. The population was 2,270 at t…Rockport is a city in Ohio Township and the county seat of Spencer County, Indiana, along the Ohio River. The population was 2,270 at the 2010 census. Once the largest community in Spencer County, the city has recently been surpassed by the town of Santa Claus. At 37°53'1" north, Rockport is also the southernmost city in the state, located slightly south of Evansville, Cannelton, or Mount Vernon.