"bus which carries passengers for a fare," 1915, short for jitney bus (1906), American English, from gitney, jetney (n.), said in a 1903 newspaper article to be a St. Louis slang for any small coin, especially "a nickel," (the buses' fare typically was a nickel), the coin name attested or suggested by 1898, probably via New Orleans from French jeton "coin-sized metal disk, slug, counter" (see jetton).
"I'll give a nickel for a kiss,"
Said Cholly to a pretty miss.
"Skiddo," she cried, "you stingy cuss,"
"You're looking for a jitney buss."
["Jitney Jingle," 1915]
The origin and signification of the word was much discussed when the buses first appeared. Some reports say the slang word for "nickel" comes from the bus; most say the reverse, however there does not seem to be much record of jitney in a coin sense before the buses came along (a writer in "The Hub," August 1915, claims to have heard and used it as a small boy in San Francisco, and reported hearsay that "It has been in use there since the days of '49"). Most sources credit it to the U.S. West, especially California, though others trace it to "southern negroes, especially in Memphis" ["The Pacific," Feb. 7, 1915].