The overall race leader wears a yellow jersey to helps him to stand out. Here Lance Armstrong wears the yellow jersey during the 2005 Tour de France.
Lance Armstrong - 2005 Tour de France
(c) Pamela Duffy
Yellow came from the page color of L'Auto, a newspaper that first sponsored the race. Though the Tour de France debuted in 1903, it wasn't until 1919 that the editor of L'Auto, Henri Desgrange, added the distinctive jersey so that spectors could pick out the leader and as another promotional tie to the paper.