In 1876, 29-year-old Thomas Edison had just opened the nation’s first research laboratory at Menlo Park, New Jersey, promising to produce “a minor invention every 10 days and a big thing every six months or so.” He kept that promise. In the next decade alone, he invented the phonograph, the incandescent light, the Dictaphone, the mimeograph machine, the electric power-plant dynamo, motion pictures, and electric transmitters. In the following six years, he founded the Edison General Electric Company to mass-produce light bulbs that eventually lit up 70 percent of all American homes and virtually all the nation’s businesses. By century’s end, 3,000 Edison power plants were illuminating the United States. Here’s the story of the man who invented modern America.