I'm a little north of you, as the crow flies. Dark Running? Reflective vest, blinking rear light (got an led band for the wrist, too), headlamp for the trails, and, for this time of year, Lifa gear (don't forget to layer up), light socks under thicker socks, light nylon glove under outer glove (though mittens are better). You want to make sure that your inside layer is polypropylene to wick moisture away from your skin else you run the risk of moisture freezing.
And most important, earmuffs (or a touque). Lifa also produces a balaclava for facial covering (that nose takes a temperature beating). A handkerchief is de rigeur, too.
Some people do have a problem with breathing through the nose in winter. If this is a problem for you, you might want to consider a face mask with a breathing tube coiled up against your chest to warm the air you're taking in. Breathing through the mouth in very cold temperatures can chill the lungs.
I have a problem with my eyes watering with exposure to cold. Since I bicycle all winter long, too, I run with my eye shields. This produces a warmer micro-environment for the eyes. Even ski goggles might be handy.
Good luck. It takes a tough person to winter run in Chicago ... or Canada.
Llarian
I'm thinking of changing my running time to early in the morning instead of after school. Of course, the sun doesn't come up until after 7 in Chicago at this time of year, and I have to get my runs finished by 6:30. What kinda gear do you all use for night running?
Thanks!