Within 15 years, George Parker's company had grown from $500 in annual sales to $110,000, with a three-story manufacturing and assembly building in Salem. When it was incorporated in 1901, Parker Brothers was the second biggest game company in the United States. Its first national hit came shortly thereafter with the British import, Ping-Pong. To play the indoor ball-bouncing game, players used small wooden paddles to hit hollow balls made out of the world's first plastic resin, a highly flammable substance, across a net stretched over a table. For "naughty fun," one could strike a match and hold it to the ball and watch the ball disappear in a flash. George Parker attempted to make Ping-Pong a legitimate sport, going so far as to organize the American Ping-Pong Association.

During the first three decades of the twentieth century, Parker Brothers produced war games (War in Cuba, Battle of Manila), travel games (Touring), and jigsaw puzzles (Pastime Puzzles). The company's success continued into the early 1930s. Ironically, the Depression provided the perfect conditions for the success of Monopoly. According to George Parker's son-in-law, Robert Barton, who became president of the company in 1933, it "was a god-send. It rescued the business, which had come within an inch of disaster. The Monopoly game . . . let people fantasize that they could win in the real estate market."

The idea for Monopoly did not originate at Parker Brothers. It began as a homemade board game created to teach students the principles of "single tax" economics. In 1904 Elizabeth Magie Phillips acquired a patent for the game but it only became a hot commercial property in the 1930s when Brace Darrow, an unemployed man from the Philadelphia suburbs, gave the game the graphic style it has to this day. George Parker played it, as he did every game submitted to him. He was intrigued but thought it was far too complicated, technical, and time-consuming to be a big seller. Darrow went ahead and self-published Monopoly in late 1934, and it was soon all the rage in Philadelphia. George Parker quickly recognized his error and bought the rights to the game.