%0 Journal Article %T Rectifiability of Optimal Transportation Plans %A Robert J. McCann %A Brendan Pass %A Micah Warren %J Mathematics %D 2010 %I arXiv %X The purpose of this note is to show that the solution to the Kantorovich optimal transportation problem is supported on a Lipschitz manifold, provided the cost is $C^{2}$ with non-singular mixed second derivative. We use this result to provide a simple proof that solutions to Monge's optimal transportation problem satisfy a change of variables equation almost everywhere. %U http://arxiv.org/abs/1003.4556v1