  In 1966 Harry Kesten settled the Erd\H os-Sz\"usz conjecture on the local
discrepancy of irrational rotations. His proof made heavy use of continued
fractions and Diophantine analysis. In this paper we give a purely topological
proof Kesten's theorem (and Oren's generalization of it) using the pattern
equivariant cohomology of aperiodic tiling spaces.
