This paper describes a method of routing in mobile ad hoc networks. The problem is exacerbated by the fact that the radio links between the nodes of the network are continually being made and broken. The method consists of using the known connections to construct a "map" of the network which is intended to reproduce the geographical layout of the network at any time. An algorithm is described which finds a route from one node to another by always attempting to move geographically closer to the destination at every hop. This produces nearly optimal performance with very short computation time. The signaling load on the system is quite low. The scaling properties of the system are investigated and it is found that the system is viable with nodes numbering in the hundreds.