In Chicago with its damnable conditions, one's sole will inevitably be tarnished. Sure, one can try to follow the narrow path away from the muck, but one misstep and the sole will be weighed down by filth. While going to a church will keep you clean for a while, you will also be inevitably dirtying to what is originally clean.
The lesson: get that snowy yuck off your shoe before stepping inside.
I used to do this by stomping, or jumping and making as hard an impact as possible. The momentum of the snow is enough to dislodge it from the bottom of the shoe, and I'm done. Today was the first time I've seen someone else do this.
Today I also witnessed someone banging their foot sideways into a wall, getting a horizontal momentum to do the same thing. That definitely requires less effort, although it would need a wall and a good balance.
My latest antic, therefore, is to knock one foot against the other. It works pretty well, actually, and it's easier than stomping around.
Remember to keep your sole clean!