What's in an H?

Since I was chastise over the spelling of Pittsburgh the other day, I decided to find out the reason why there was an h on the end of Pittsburgh...
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What's in a name? Well, if it's Pittsburgh, then it's an 'h.' If you've never noticed, Pittsburgh spells its name with an 'h' at the end. Of the many other Pittsburgs in the USA, including some 20 towns in New Hampshire, Maine, Illinois, Kansas, California, and Texas, all spell their name without the ending 'h.'

'The Artist formerly Known as Prince' isn't the only one whose name has caused confusion. While residents are well aware that the city spells its name with the unusual ending, others may not. Most citizens with a Pittsburgh mailing address have at one time or another received a piece of mail with the city's name spelled incorrectly. It looks so peculiar-- as if it is only half dressed.

More here: http://www.popularpittsburgh.com/pittsburgh-info/pittsburgh-history/whatsinanh.aspx