A footprint location system installed on footwear is disclosed. A user simply has to wear the shoes to track his/her locations without any setup or calibration efforts. The footprint location system measures and tracks the displacement vectors along a trail of footprints. The position of a user can be determined by summing up the current and all previous displacement vectors. In addition to being infrastructure-free, the footprint location method does not have problems found in existing indoor location systems, such as obstacles, multi-path effects, signal noises, signal interferences, and dead spots.