Pittsburgh, named by General John Forbes in honor of Sir William Pitt, the first Earl of Chatham (15 November 1708 – 11 May 1778), has officially ended in an ‘h’ since its founding in 1758 with the exception of the time period from
1890-1911.
In 1890, President Benjamin Harrison formed a committee to “normalize” the spelling of towns formulated the following rules – and that reulted in things we see today -
a) The avoidance, so far as seems practicable, of the possessive form of names.
(b) The dropping of the final “h” in the termination “burgh.”
(c) The abbreviation of “borough” to “boro.”
(d) The spelling of the word “center” as here given.
(e) The discontinuance of the use of hyphens in connecting parts of names.
(f) The omission wherever practicable of the letters “C.H.” (Court House) after the names of county seats.
(g) The simplification of names consisting of more than one word by their combination into one word.
(h) The avoidance of the use of diacritic characters.
(i) The dropping of the words “city” and “town” as parts of names.
The proud citizens of Pittsburgh, considering their town an obvious historical exception to this ruling, refused to give in to the Board's ruling and mounted a campaign to keep the traditional spelling. Twenty years later, in 1911, the Board
finally relented and restored the 'h' to Pittsburgh.
To this day people remain confused.
Pittsburgh, Pennsylvania is not the only Pittsburg(h) in the nation. There's even a tiny town in North Dakota that spells it with the "h".