Original caption:
Distribution of the broods of the 13-year race of the Periodical Cicada (after Marlatt).
(Caption corrected, 17-year to 13-year 20 December 2015.)
From:
The periodical cicada / by Wm. J. Gerhard, Assoc. Curator of Insects. Leaflet (Field Museum of Natural History. Dept. of Zoology) ; no. 4 (1923).
Direct links: maps, bibliographic entry
Note that the exact distribution indicated by the dots may have been superseded by more current research, but these maps serve to show the general distribution of 13-year and 17-year broods.