Today I was riding in a car going down the interstate (no way to stop for pictures) and I saw a bird I didn't recognize. Here's the description in a nutshell. The bird was sitting on a fence post or dead tree stump on the edge of the highway beside a large field, it had stark black wings, shoulders, head and a stark white chest. It was about the size of a red-tailed hawk and was looking straight at me so I couldn't tell what it's beak looked like. It was in western Illinois in the upper third of the state. I know it wasn't a bald eagle because it had a black head and was smaller than a mature eagle...even a male. That's what the coloring looked like tho, definite contrast between the black and white and both very much true to color...no brown in the black or white! Any ideas?

TIA