Simplify the following text for a Grade 9 native English-speaking person.
Original: Joshua Abraham Norton ( c. 1819 â `` January 8 , 1880 ) , the self-proclaimed Imperial Majesty Emperor Norton I , was a celebrated citizen of San Francisco , California , who in 1859 proclaimed himself `` Emperor of these United States '' and subsequently `` Protector of Mexico '' .
Simplified: Joshua Abraham Norton , or Emperor Norton ( 1819 ? - 1880 ) was a man who declared himself Emperor of the United States and Protector of Mexico .