Dude! Who says that?

So check this out. According to the Random House Historical Dictionary of American Slang, an 1877 reference from the painter and sculptor Frederick Remington states: "Don't send me any more [drawings of] women or any more dudes" This was the first recoded use of the word. By 1883, dude was in wide use. In June of that same year its popularity was noted in a recording of the North Adams Transcript:

"The new coined word 'dude'...has traveled over the country with a great deal of rapidity since but two months ago it grew into general use in New York." By 1885, it was in such common use that it appeared in an entry in Ulysses S. Grant's Personal Memoirs: "Before the car I was in had started, a dapper little fellow--he would be called a dude at this day--stepped in."

Source: Randomhouse.com : The Mavens' Word of the Day, June 21, 2001