A system and method are disclosed for using magnetic signatures at predetermined positions along a roadway to monitor traffic travelling along the roadway by comparing the predetermined magnetic signatures with magnetic signatures being dynamically and continuously measured by each vehicle as they travel along the roadway. Magnetometers incorporated into mobile devices or otherwise incorporated within the vehicle measure magnetic signatures for comparison to the predetermined magnetic signatures that form a connection graph or database of points that correspond to possible paths along a roadway. When a magnetic signature match is made, the system recognizes that the vehicle has passed a particular point on a roadway and forwards that information to the appropriate entity for further processing, analysis, or toll assessment.