From wikipedia:
Feral pigs are a growing problem in the United States and also on the southern prairies in Canada. As of 2013, the estimated population of 6 million feral pigs causes billions of dollars in property and agricultural damage every year in the United States, both in wild and agricultural lands. Their ecological damage may be equally problematic with 26% lower vertebrate species richness in forest fragments they have invaded. Because pigs forage by rooting for their food under the ground with their snouts and tusks, a group of feral pigs can damage acres of planted fields in just a few nights. Because of the feral pig's omnivorous nature, it is a danger to both plants and animals endemic to the area it is invading. Game animals such as deer and turkeys, and more specifically, flora such as the Opuntia plant have been especially affected by the feral hog's aggressive competition for resources. Feral pigs have been determined to be potential hosts for at least 34 pathogens that can be transmitted to livestock, wildlife, and humans. For commercial pig farmers, great concern exists that some of the hogs could be a vector for swine fever to return to the U.S., which has been extinct in America since 1978. Feral pigs could also present an immediate threat to "nonbiosecure" domestic pig facilities because of their likeliness to harbor and spread pathogens, particularly the protozoan Sarcocystis.
By the early 2000s, the range of feral pigs included all of the U.S. south of 36° north. The range begins in the mountains surrounding California and crosses over the mountains, continuing consistently much farther east towards the Louisiana bayous and forests, terminating in the entire Florida peninsula. In the East, the range expands northward to include most of the forested areas and swamps of the Southeast, and from there goes north along the Appalachian Mountains as far as upstate New York, with a growing presence in states bordering West Virginia and Kentucky. Texas has the largest estimated population of 2.5–2.6 million feral pigs existing in 253 of its 254 counties., and they cause about $50 million in agriculture damage per year.
