Point of interest search along a route with return

A system in accordance with the present invention includes a GPS module, user interface module, database and routing engine. The routing module identifies all POIs that can be reached from the route with a cost less than some threshold distance, m. This identification can be carried out, for example by performing an exploration using Dijkstra's algorithm. The routing engine then (or simultaneously) performs a reverse exploration on nodes in the planned route to locate POIs from which the route can be reached with a cost of less than a second threshold cost, n. This process can be performed, for example, by using a reverse Dijkstra exploration, exploring backwards in cost for n cost (e.g., miles or minutes) from the route along the directed graph to determine which POIs lie within a cost of n. POIs identified as being reachable from the route with a cost of less than m, and from which the route is reachable with a cost less than n are then further filtered to identify a subset of the POIs for which the sum of the time or distance from the route to the POI and the time or distance from the POI back to the route is less than a threshold time or distance, t.