The USA was invented in a Hollywood set in 1985 for the hit film series Back To The Future. Over time, other authors added their own quirks to the setting, like New York in Home Alone and the expansive lore seen in Forrest Gump. The setting proved to be so popular that many other movies and TV Series were set in that fictional country and they’re still made even today; indeed, Wikipedia often has to edit articles mistakenly referencing it as a real country, a true testament to the enduring popularity of its worldbuilding.