DuPage County IllinoisDuPage County DOT Great Western Trail and Illinois Prairie Path Mile Posts. Note: The zero mile post for the Great Western trail is at the eastern terminus of the trail. Mileage increases to the west along the Great Western Trail. The zero mile post for the Illinois Prairie Path System is at Liberty Dr and Carlton Av in Wheaton.ArcGIS FeatureLayerhttps://hub.arcgis.com/datasets/ef2b36b8b3424eee8cb7f56e96713be7_0engDuPage County GISPublicTrail Mile Posts [Illinois--DuPage County]Web servicesIllinois--DuPage CountyIllinoisLast Modified: 2015-12-17