The pathogen Phytophthora ramorum, known to cause sudden oak death on the West coast of the U.S., occurs in North America as three distinct clonal lineages [1]. Here we present a map of the occurrence of the pathogen P. ramorum in U.S. nurseries. The map can be set to display observations by clonal lineage. We use a method called microsatellites (or simple sequence repeats) to place P. ramorum individuals into one of four currently globally recognized clonal lineages named NA1, NA2, EU1, and EU2 [2]. The EU2 lineage has not been observed in the U.S.