I got chased off the on-ramp in Coeur d'Alene, ID, by a real asshole of a city cop. Said it was against state law to hitch, but the DigiHitch road guide provided here suggests that on-ramps are okay in Idaho.
Anyway, I walked to the police station to talk to the commanding officer on shift that day (a Lieutenant Dickson) and when I told him the story of his jerkoff patrolman, the Lt. mentioned that there's a city law against hitching.
So, I dunno - maybe there's a city law that prohibits "solicitations" even from the on-ramp, but maybe not. I wish I'd had this on me at the time, will certainly be appreciated in the future, but ultimately if the cop pulls out the cuffs, I'm not sure I'm really wiling to test the legality of their on-ramps.
Maybe, when I'm just traveling with no deadlines or schedule.