For a little over a century now, wire has been the term used to mean the finish line in horse racing because of the wire stretched across the track which the horses passed under at the end of the race. According to the Oxford English Dictionary, wire has been used at least since 1902, when it was recorded A.D. McFaul's Ike Glidden in Maine: 'The conquering colt swept under the wire for a nose ahead of the trotter.' However, A Dictionary of Americanisms sites an 1887 newspaper article that uses wire in this way. Dictionary also dates the expansion of this term into our phrase down to the wire from 1950, when it was first recorded in a newspaper account of a baseball game and meant 'to the very last moment, the very end.'