I'm not sure, but probably every State in the union has driving laws stipulating that you are to turn on your headlights 1 hour before sunset, or during inclement weather. Why are there so many who fail to 'light up', when it's been proven safety is greatly improved if a vehicle has the headlights on. The first clue [if you have failed to notice the sun has already set] is that most businesses have turned on their outside lights. Another clue, is the fact that you are unable to read the [analog] guages/speedometer of your vehicle, due to not having the lights on. Conversely, I really get irritated with the folks who only apparently only have enough strength to activate the parking lights, yet are unable to move the lever/switch to the headlights on position. I see them practically every evening, after sunset, and even though I flick my headlights at them, they seem oblivious to their situational awareness.