Illinois law requires that headlights be on when atmospheric conditions require the use of windshield wipers.

Illinois law mandates that drivers must turn on their headlights when windshield wipers are necessary due to atmospheric conditions. This regulation is put in place for safety reasons, as reduced visibility during rain, fog, or snow can make it difficult for drivers to see the road and for others to see vehicles. Headlights enhance visibility for both the driver and other road users, helping to reduce the risk of accidents in poor weather conditions. This requirement aligns with similar regulations in many other states, reinforcing the importance of maintaining visibility while driving. It reflects the principle that safe driving practices should be maintained during adverse weather conditions.