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The invasive wild pigs (Sus scrofa; pictured) compete with the country's native wildlife and cost the agricultural industry more than US$1.5 billion a year. To predict their future spread, Nathan Snow, now at the USDA National Wildlife Research Center in Fort Collins, Colorado, and his colleagues modelled the distribution of wild pigs in the continental United States from 1982 to 2012. The authors found that, during this period, the pigs' rate of northward range expansion accelerated from 6.5 kilometres to 12.6 kilometres per year. If this trend persists, wild pigs are predicted to reach most counties in 30–50 years.