At first glance, it may appear that you only have one map layer displayed in the map view. This is because both the Counties and State Outline layers contain polygon features, and both files are currently using solid shading. When this happens, the polygons on top will obscure features underneath:
- Deselect the checkbox next to Counties to turn off the layer. When you turn off the layer, you should see the Illinois outline layer. Turn the Counties layer back on.