Pennsylvania: Earlier in 1904, a fellow–Pennsylvanian Quaker woman name Elizabeth (Lizzie) J. Magie Philips had actually invented/created—and patented—it’s direct ancestor board game, The Landlord’s Game.
Eventually (by the mid–1980s!) Parker Brothers, now a subsidiary of Hasbro, would fully buy out both of their patents, and finally settle all lawsuits.
MONOPOLY is widely considered the most popular commercial board game of all time. (Presumably non–commercial classics – historic chess, monopoly, shesh besh and checkers—were not in the counting.)
Monopoly has much lore surrounding its 70+ year tenure to date. On the British front during WWII, in 1941 the British Secret Service had John Waddington, Ltd., the licensed manufacturer of the game outside the USA; surreptitiously create a “special edition” of the game, which it eventually got past Nazi security via the Red Cross into the hands of Allied prisoners in Nazi POW camps. The “special edition” had hidden inside it, maps, compasses, and currency, which the POWs could use to aid in escaping. Presumably, the Red Cross was unawares.
The 1999 Guinness Book of Records, cites Hasbro’s previously articulated statistic of 500 million people as having played the game worldwide. (Later, the firm will up the figure by 50%).
There are local versions in various international capitals, customized for the locals, e.g. in London and Moscow.
On the local front, my personal preference is actually “Risk,” released in 1957 (I was seven), originally invented by the French movie film director Albert Lamorisse. The original name of that game was “La Conquête du Monde” (The Conquest of the World). The French had some prior practice. Also by Parker Brothers–Hasbro.