While living in Louisiana from 1974 to 1981, I did a lot of deer hunting in NW LA. The area we hunted was hundreds of acres and besides being great deer hunting, it also had a lot of feral pigs. They would root around and drive you crazy while sitting on a deer stand. Had a few come in close to me, but never did get a shot off.
They did not come down into the cities, but the digging they did in the woods was remarkable. Not that my lawn up here is that great, but I certainly hope they do not make it to Alton.