This guide is for general information only and is not legal advice. Laws change — verify current rules with your state DOT or a licensed attorney before relying on this for any legal matter. Read full disclaimer.
The rule
Illinois requires lamp on the front emitting a white light visible from at least 500 feet to the front. For the rear, red rear reflector of an idot-approved type visible from 100 to 600 feet when directly in front of low-beam headlamps. a red rear lamp visible from 500 feet may be used in addition to — or, under the 2017 amendment, in lieu of — the reflector. The rule applies whenever it is dark. See 625 ILCS 5/11-1507.
The cheapest way to stay legal in Illinois is a USB-rechargeable front white light and a rear red light or reflector that meets the spec above. A $30 light set covers it.