A system and method for the use of geo-fences to coordinate and track delivery of items. In some embodiments, the system comprising a mobile delivery device comprising a vector calculation module configured to determine a motion vector associated with the mobile delivery device, a geo-location module configured to determine a geo-location associated with a mobile delivery device, and a geo-fence database configured to determine a size of at least one geo-fence associated with at least one location and determine whether the mobile delivery device is within the geo-fence. In some embodiments, the size of the geo-fence is determined at least in part on the motion vector determined by the vector calculation module.