In my expiriance anyway .. it really depends upon which map you are looking at to determine boundry in some instances .... 'spcecilly when there is no defined natural(ie: river) or landmark(ie: road etc...)...if you really want them park critters ... Then i would suggest investing in a good GPS and and up to date software and landmark those boundrys on your gps .... and get as close as you can without goin over ... and wait ... best do it before GOS as then when the first BOOM of the year them critters know whats safe zone ...