How did giant corporations transform America's economy in the second half of the nineteenth century?

In the second half of the nineteenth century, America's industrial corporations grew to enormous size. The first large business corporations were railroad companies, which grew rapidly beginning in the 1850s. In 1860, the U.S. had 30,000 miles of railroad track. The transcontinental line was finished in 1869, linking the Atlantic and Pacific oceans by rail. By 1900, the nation had more than 200,000 miles of track, more than half of the railroad mileage in the world. Railroad companies and owners exercised tremendous influence not only in American business, but in politics as well.

The growth of railroads contributed to the growth of other industries. Steel production also grew rapidly in the late nineteenth century. The Bessemer converter, an important innovation, enabled manufacturers to purify iron into steel much more efficiently. Steel production increased by ten times between 1877 and 1892, and much of this steel was made into rails for American railroad tracks. Andrew Carnegie, the nation's leading steel magnate, became the wealthiest man in the world. In 1901, financier J.P. Morgan purchased Carnegie's company for $450 million dollars and created the U.S. Steel Corporation. Carnegie, who came to the U.S. as a poor Scottish immigrant, devoted his later years to charitable pursuits, donating money to build libraries and to other public causes.

Other industries, such as copper (used for electrical wire), oil, and coal also grew quickly between 1850 and 1900. John D. Rockefeller entered the oil business in the 1860s in Ohio, and founded the Standard Oil corporation in 1870. Rockefeller expanded his company, gaining ownership not only of oil wells, but of refineries, warehouses, and transportation. By the 1880s, Rockefeller controlled 90 percent of American oil production.