A mile and a quarter
The first Kentucky Derby was held in 1875.
The Winner was "Mine that Bird", jockey Calvin Borel
Joe Talamoe is a 19year old jockey who is still looking to winning every jockeys dream,the Kentucy Derby.
There are 17 Kentucky Derby winners that are still living. They include Giacomo, Smarty Jones, Funny Cide, War Emblem, and Charismatic.
Derby County were the FA cup winners for the 1945 season.
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There have been 136 winners of the Kentucky Derby thus far. The winners of the inaugural Derby of May 17, 1875 were the horse Aristides and the rider Oliver Lewis [1856 - 1924]. The winners of the 136th Derby of May 1, 2010 were the horse Super Saver [foaled 2007] and the rider Calvin H. Borel [b. November 8, 1966].
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The full list of winners is available at the link below.
I will assume by "derby" you mean Kentucky Derby. I will also assume that you only mean winners of the Derby. There have been two Derby-winning horses with 15 letters in their names: Foolish Pleasure (1975) and Fusaichi Pegasus (2000).
It is in Kentucky.