She invented The Landlord's Game, the precursor to Monopoly, to illustrate teachings of the progressive era economist Henry George.

At the age of 26, Magie received a patent for her invention that made the typewriting process easier by allowing paper to go through the rollers more easily.

[2] Magie was an outspoken activist for the feminist movement, and Georgism, which reflected her father's political beliefs when she was young.

In order to bring the struggles of women in the United States to the public's attention, she bought an advertisement and tried to auction herself off as a "young woman American slave" looking for a husband to own her.

In the following patents, the game developed to eventually have two different settings: one being the monopolist set up (known as Monopoly) where the goal was to own industries, create monopolies, and win by forcing others out of their industries and the other being the anti-monopolist setup (known as Prosperity) where the goal was to create products and interact with opponents[citation needed].

As her original patent had expired in 1921, this is seen as her attempt to reassert control over her game, which was now being played at some colleges where students made their own copies.

In Bargain Day, shoppers compete with each other in a department store;[8] King's Men is an abstract strategy game.

She was buried with her husband Albert Wallace Phillips, who had died in 1937, in Columbia Gardens Cemetery, Arlington, Virginia.

College students attending Harvard, Columbia, and University of Pennsylvania, left-leaning middle-class families, and Quakers were all playing her board game.

[12] Darrow was known as the inventor of Monopoly until Ralph Anspach, creator of the Anti-Monopoly game, discovered Magie's patents.

Anspach had researched the history of Monopoly in relation to a legal struggle against Parker Brothers regarding his own game, and discovered Darrow's decision to take credit for its invention, despite his having learned about it through friends.

[2] It was only after her death that the impact Magie had on many aspects of American culture and life began to be appreciated[citation needed].