Abstract: A routing method for differential current switch (DCS) pairs initially shortens the min/max length window for a first routed rail in order to increase the likelihood that length of the second rail will fall within the window. Next, the routing domain for the first rail is modified so that the first pin exit direction to the route is toward the second pin of the differential current switch pair. A suitable algorithm, such as a prior art mazerouter algorithm, is used to route the first rail along a path restricted to the routing domain. At each proposed via connection for connecting the first rail route from one plane to another, the program accepts the proposed via connection only if there is an available adjacent via for routing the second via. If a via for routing the second rail is not available, the proposed route for the first rail is rejected.