Pittsburgh's access to large reserves of raw materials, especially coal, was instrumental to the emergence of the “Steel City” as a leading industrial center in the late 19th century.
By the 1920's Pittsburgh produced 
one
third of the national output of finished and rolled steel. It had the world's largest tube and pipe mill, structural steel plant, rail mill, wire manufacturing plant, bridge and construction fabricating plant. Pittsburgh also led in the manufacture of electrical machinery, railroad cars, tin plate, glass, fire brick and aluminum finishing. Forty percent of the nation's coal came from within 100 miles of Pittsburgh.
The heavy reliance on the metals industries resulted in economic stagnation and decline in the Pittsburgh economy when these industries experienced decreased demand and increased competition from foreign producers. After the mid-1970s, as the number of those employed in the steel industry declined, the city's economic base underwent a dramatic shift from manufacturing to service industries and commercial enterprises. Once a major center for corporate headquarters, many departed in the 1990s, a period, however, that saw the growth of high-technology companies. ..............................................................................Pittsburgh steel mill in 1890
As we mentioned earlier, the earlier growth of Pittsburgh and its economy was caused by the extensive trade of steel. Since, Pittsburgh has adapted to the collapse of the region's steel industry. The "Golden Triangle" of the downtown has been renovated. The primary industries have shifted more to high technology, such as robotics, health care, nuclear engineering, tourism, biomedical technology, finance, and services. Education is also a major employer, from primary through magnet schools, specialized professional institutes and highly-ranked universities.
In fact, Pittsburgh still maintains its status as a corporate headquarters city, with seven Fortune 500 companies calling the city home. This ranks Pittsburgh in a tie for the sixth-most Fortune 500 headquarters in the nation. In 2006, Expansion Magazine ranked Pittsburgh among the top 10 metropolitan areas in the nation for climates favorable to business expansion. Pittsburgh is the headquarters of many major corporations; e.g. U.S. Steel, Gulf Oil, Westinghouse Electric, Rockwell International, Alcoa, National Steel, PPG Industries, H.J. Heinz. Next to New York and Chicago, Pittsburgh is the most important city for corporate headquarters.
The following is a summary of data regarding the Pittsburgh metropolitan area labor force, 2004 annual averages.
• Size of nonagricultural labor force: 1,134,700
• Number of workers employed in . . .
• construction and mining: 58,900
• manufacturing: 103,300
• trade, transportation and utilities: 233,700
• information: 24,100
• financial activities: 69,600
• professional and business services: 138,900
• educational and health services: 213,500
• leisure and hospitality: 105,100
• other services: 59,500
• government: 128,100
all data and images were obtained from: www.explorepahistory.com and www.city-data.com
