These data obtained from the peer-reviewed literature and a public database depict the geographic expansion of the black-legged tick (Ixodes scapularis) and human cases of Lyme disease in the midwestern U.S.

Note: There was an omission from the first version (V1) of the data set that required us to update the data. Specifically, we failed to include the data from the article "Caporale DA, Johnson CM, Millard BJ. 2005 Presence of Borrelia burgdorferi (Spirochaetales: Spirochaetaceae) in Southern Kettle Moraine State Forest, Wisconsin, and characterization of strain W97F51. J. Med. Entomol. 42, 457–472". In the second version (V2) of the data, this omission is corrected.