This has been discussed on here some before. The Smithsonian for Jan 2011 has an article on wild hogs, with a map showing growth in infestation from 1982 to 2010. Surprisingly, almost all of CA has wild hogs except the extreme Southeastern desert areas.TX has the most. The upper Great Plains and the Midwest are not so thickly populated but oddly enough MI has them all over the state including the UP. The article says that Canada has some also.
Hogs have no natural predators and there are no legal poisons to use.There are 2 million to 6 million of them and in TX they do $400 million in damages yearly.
To be sold commercially as meat in TX, wild hogs must be taken alive to one of about 100 statewide buying stations. 461,000 TX wild higs were processed between 2004 and 2009. There is a small but growing US market, but most meat end up in Europe and Southeast Asia.
I haven't seen any on my place in Western SC yet, but there are reports of some around. Oh, BTW, they go into suburban areas also.