The 'crank' is a partition statistic which originally arose to give combinatorial interpretations for Ramanujan's famous partition congruences. In this paper, we establish an asymptotic formula and a family of Ramanujan type congruences satisfied by the number of partitions of n with even crank M e (n) minus the number of partitions of n with odd crank M o (n). We also discuss the combinatorial implications of q-series identities involving M e (n) − M o (n). Finally, we determine the exact values of M e (n) − M o (n) in the case of partitions into distinct parts. These values are at most two, and zero for infinitely many n.