Xanthomonas citri pv. citri (Xcc) causes the devastating citrus canker disease. Xcc is known to have been introduced into Florida, USA in at least three different events in 1915, 1986 and 1995 with the first two claimed to be eradicated. Here, we investigated the population structure of Xcc to understand the mysteries related to its introduction, spread and eradication, and how Xcc strains have evolved in term of pathogenicity and copper resistance. We sequenced whole genome sequences of 343 Xcc strains collected from Florida groves over 20 years.