Periodical cicadas of the genus Magicicada are commonly found throughout the Eastern United States, and their loud mating calls can be heard every 13 or 17 years as various broods of nymphs emerge in massive numbers.These cicadas have a tremendous impact on their ecosystems, including serving as a critical food source for many species during years in which they emerge. Magicicada emergences have even been known to have measurable impacts on avian abundance in the years following large broods. Despite the important roles these insects play, researchers have struggled to make sense of the many unique characteristics of these peculiar insects, including their abnormally lengthy life cycles, population structure, and evolutionary history. Studies have suggested that low effective population sizes (Ne) might help explain observed life cycle patterns and subsequent speciation. To investigate these questions, we analyzed the recently published whole genome sequences of two 17-year periodical cicada species (M. septendecim & M. septendecula) from Brood X. We estimated their effective population sizes over time using the Pairwise Sequential Markovian Coalescent (PSMC) analysis. Additionally, we conducted quality assessments on the current genomic resources to investigate the strength of the inferences made. Finally, we share insights learned from our current work on sequencing, assembling and annotating the genome of the third Brood X species (M. cassini). We show here that whole genome analyses can provide unique and valuable insights into answering quesions surrounding the evolutionary history and population growth of periodical cicadas.