Figure 1.

From Eisen et al J Med Entomol 201650 with permission. Changes in county status for Ixodes scapularis and Ixodes pacificus from December 1996 to August 2015. Black color indicates that county status already was established (black) or reported (gray) for I. scapularis or I. pacificus and considered to be the same in this study. Red or orange color indicates that the status of a county changed from no records to established (red) or from reported to established (orange). Green color indicates that the status of a county changed from no records to reported.