Appalachia
With Pittsburgh being on the outskirts of the Appalachia region, coal is found in the foothills near the city. Coal is what put the city on the map and made it an important part of U.S history. Coal seems were discovered in the plateaus, and were exposed by the rivers and stream's erosive powers. These seems of coal are what powered Pittsburgh steel mills. According to William Edmund, from his book, Coal in Pennsylvania, " The earliest record of actual coal mining in Pennsylvania is shown on a “Plan of Fort Pitt and Parts Adjacent” in 1761. Fort Pitt was located in what is now downtown Pittsburgh where the Allegheny and Monongahela Rivers join to form the Ohio River. The mine was located across the Monongahela River near the top of Coal Hill (now called Duquesne Heights). These early miners removed the first few tons of coal from the fabulous Pittsburgh seam, which has been called, with considerable justice, the world’s most valuable single mineral deposit." With the rich deposit of coal, mining became a major industry in Western Pennsylvania. The mines gave new job opportunities to immigrants and neighborhoods in Pittsburgh began to swell in the 1800's and 1900's. The immigrants brought with them their rich culture and religions.Today many of the mines have been closed since the 1980's. When the mines closed the ethnic culture began to leave Pittsburgh since people had to search for new job opportunities else where.

Sources:
http://pittsburgh.about.com/gi/dynamic/offsite.htm?site=http%3A%2F%2Fwww.dcnr.state.pa.us%2Ftopogeo%2Feducation%2Fcoal%2Fes7.pdf
http://www.coalcampusa.com/westpa/index.html
http://images.asc.ohio-state.edu/is/image/eHistory/mmh/doc_humanmachinery/coalminers.jpg