[5] Under Pennsylvania legal classifications for local governments, Clairton is considered a third-class city.

Clairton's existence dates to just after the turn of the 20th century, when the Crucible Steel Company acquired a large tract along the west side of the Monongahela River, approximately 13 miles (21 km) south of Pittsburgh.

Clairton took on a life of its own, including a business district and educational, religious, and cultural facilities.

During the mid-1950s and into the 1960s, CHS was a Class AAA competitor in the formidable Western Pennsylvania Interscholastic Athletic League (WPIAL), playing against high schools in other mill towns up and down the Monongahela River Valley.

With the decline of the steel industry in the 1980s, Clairton began to experience severe problems in its employment and tax base, which spurred a major economic shock to the community.

In 1988, Clairton was designated a distressed municipality by Pennsylvania's Department of Community Affairs (DCA).

The city was the setting for the movie The Deer Hunter (1978), the steel town where the American characters live.

Even the opening scene, which features a large sign saying "Welcome to Clairton, City of Prayer," was shot in Mingo Junction, Ohio.

Much of the 1979 Marvel comic book ROM: Spaceknight is set in a fictional version of Clairton, located in West Virginia instead of Pennsylvania.

In 2011, former Marvel Editor-in-Chief Jim Shooter explained that the change in location was made to benefit the story.