In networks where nodes are aware of their locations via the use of a GPS receiver or other localization techniques, geographic routing has been suggested to be the candidate of choice for robust and resource efficient routing. However, efficient location management algorithms are required for the source node to obtain the destination node's location before it can start data transfer using geographic routing. To be deemed scalable with respect to network size, mobility and traffic, the signaling overhead due to location management must be kept low so that the performance of geographic routing is minimally affected. This paper describes the performance of a novel multi-level hierarchical grid location management protocol that we call HGRID, for large scale ad hoc networks. We show that the average per node signaling cost in HGRID grows only logarithmically in the total number of nodes in a uniformly randomly distributed network—a substantial improvement over the signaling cost incurred by current location management schemes. We also carry out extensive simulations to quantitatively compare the performance of the protocol against other well known location management protocols, and to study how location management can affect the scalability of geographic routing. Results show that our protocol outperforms others in terms of network throughput and end-to-end packet delay with increasing network size or average node speed. Thus hierarchical grid location management scales well for large scale mobile ad hoc networks.