These data were compiled to investigate the demographic, phylogeographic, and adaptation history of Hilaria jamesii. The data release consists of three tab delimited text files that may be used to infer population structure or putative adaptive loci (hija_adaptation_dataset.stru), relationships among sampling localities (hija_phylogeny_dataset.phylip), or genetic diversity statistics (hija_diversity_stats.vcf). All files record genetic variation on an individual (.stru and .vcf) or sampling locality (.phylip) level. The .vcf file contains all of the information contained in the other files, but the file structures vary based on the programs used for analysis. These files may be opened and edited in a text editor program, such as Notepad ++ (PC) or BBEdit (Mac). The .vcf file can be loaded into the Stacks population program (Catchen et al. 2013) to calculate genetic diversity statistics. The .phylip file can be uploaded to phyML to generate a tree-based visualization of relationships ( http://www.atgc-montpellier.fr/phyml/). The .stru file can be used in the STRUCTURE program (Falush et al. 2007) to estimate population structure.