Born in England in 1811, who was the only self-proclaimed "emperor" in the United States?

Joshua Abraham Norton:

"September 17, 1859, when he citywide proclaimed himself emperor. The first call as Majesty was as follows: "I beordere February 1 next year, all the representatives of the Union State in the urban Music Hall to there myself to make such legislative changes, which are suitable to eliminate the evils afflicting the country." the call went into the void of course, no one took seriously Norton."

Generally speaking, no one thought he was being serious, but he was a well liked fellow and most people just let him roll with it, despite there clearly being something unstable with him. Fun fact, he also made his own currency!

https://medium.com/@ingolackerbauer/americas-first-and-last-emperor-norton-i-8dcf380b132b