Idaho Ditches Mile Marker '420' So Stoners Won't Steal It Instead, drivers will pass marker 419.9 By Newser Editors and Wire Services Posted Aug 18, 2015 8:09 PM CDT 29 comments Comments The new mile marker just south of Coeur d'Alene, Idaho. (Kathy Plonka/The Spokesman-Review via AP) (Newser) – If you're looking for milepost 420, you won't find it in on a stretch of highway near Coeur d'Alene, Idaho. State transportation officials say the mile marker on US Highway 95 has been replaced with one for 419.9—to curb thieves eager to own a number associated with marijuana enthusiasts. Turns out, Idaho isn't alone in this problem. States like Washington and Colorado also have replaced 420 signs with 419.9. It's generally not an issue in most states, however, because highways usually don't cover more than 400 miles.