Emerald ash borer (EAB), a nonnative invasive bark boring beetle discovered near Detroit, MI, and Windsor, Ontario, in 2002, is now found in fourteen states and two Canadian provinces (May 2010) and is causing widespread ash mortality in urban forests. NRS scientist Robert Haight was a member of a working group that assessed the economic impacts of non-native forest pests, including EAB. The group, supported by The Nature Conservancy (TNC) and The National Center for Ecological Analysis and Synthesis, was convened in 2007-2010 and included scientists from the Forest Service (three research stations and the Washington Office), TNC, and four universities. The group predicted the discounted cost of landscape ash treatment, removal, and replacement on developed land within communities in a 25-state study area centered on Detroit using simulations of EAB spread from 2009-2019. An estimated 38 million ash trees grow on this land base. The simulations predicted an expanding EAB infestation that will encompass most of the 25 states and warrant treatment, removal, and replacement of more than 17 million ash trees with discounted cost of $10.7 billion.