In the first 5 years after its introduction in the United States in 1999, West Nile virus (WNV) spread to the 48 contiguous states, resulting in 667 reported deaths. To establish detection and response capacity, WNV surveillance and prevention was supported through CDC Epidemiology and Laboratory Capacity (ELC) cooperative agreements with all 50 states and six large cities/counties. In 2005, the Council of State and Territorial Epidemiologists (CSTE) conducted an assessment of ELC recipients and determined that, since 1999, all had developed WNV surveillance and control programs, resulting in a national arboviral surveillance infrastructure. From 2004 to 2012, ELC funding for WNV surveillance decreased by 61%. In 2012, the United States had its most severe WNV season since 2003, prompting a follow-up assessment of the capacity of ELC-supported WNV programs. Since the first assessment, 22% of jurisdictions had stopped conducting active human surveillance, 13% had stopped mosquito surveillance, 70% had reduced mosquito trapping and testing, and 64% had eliminated avian mortality surveillance. Reduction in early detection capacity compromises local and national ability to rapidly detect changes in WNV and other arboviral activity and to initiate prevention measures. Each jurisdiction is encouraged to review its current surveillance systems in light of the local threat of WNV and emerging arboviruses (e.g., dengue and chikungunya) and ensure it is able to rapidly detect and respond to critical changes in arbovirus activity.