Glassport is a borough in Allegheny County, Pennsylvania, United States, approximately 10 miles (16 km) south of Pittsburgh and the confluence of the Monongahela and Allegheny rivers where they form the Ohio River. Glassport lies along the east side of the Monongahela river in the "Mon valley", where many blue-collar municipalities have suffered severe economic decline in the wake of the loss of steel-making throughout the Greater Pittsburgh Area. In 1910, the population of Glassport was 5,540. By 1940, it had risen to 8,748, but has since declined to 4,993 as of the 2000 census.
According to the United States Census Bureau, the borough has a total area of 1.9 square miles (4.9 km2), of which, 1.7 square miles (4.4 km2) of it is land and 0.2 square miles (0.5 km2) of it (11.05%) is water.
As of the census of 2000, there were 4,993 people, 2,187 households, and 1,355 families residing in the borough. The population density was 2,968.5 people per square mile (1,147.5/km2). There were 2,405 housing units at an average density of 1,429.8 per square mile (552.7/km2). The racial makeup of the borough was 98.24% White, 0.56% African American, 0.28% Native American, 0.18% Asian, 0.06% Pacific Islander, 0.18% from other races, and 0.50% from two or more races. Hispanic or Latino of any race were 0.82% of the population. 22.4% were of Polish, 22.0% Italian, 13.0% German, 8.7% Irish, 7.9% Slovak and 5.6% English ancestry according to census 2000.