Do you drive slowly up mountains under 40 MPH with 4-way hazard lights flashing so all behind, day or night know that we are far under the highway speed limit? <br/><br/>Well, just read to my surprise, this safe driving habit is clearly illegal in most states. <br/><br/>Map shows a summary of state laws.<br/><br/>Looks like we are only going to turn on flashers when we are parked.