Palmer amaranth (Amaranthus palmeri S. Watson), a plant species native to the southwestern United States, is a significant challenge in modern weed management, recently establishing itself in agroecosystems within the Californian Central Valley in 2015. Palmer amaranth’s range expansion potential is well-documented in the eastern U.S. The expansion into Central California warrants an examination of where the new weed infestations fit into the population structure of Palmer amaranth in the western United States, and what differences in population genetic statistics may exist between these emerging populations and those in the native range. I have conducted populationlevel sampling from both these regions and generated genomic data to identify genetic variants (single-nucleotide polymorphisms) for population genetic analysis. I conducted both STRUCTURE and ADMIXTURE analyses with an original dataset (n = 113). These analyses indicate a scenario of K= 2 ancestral genetic clusters is most likely given the data. STRUCTURE ancestry estimates indicate that Californian samples from the invade range do not possess a pattern of estimated ancestry atypical to the region ADMIXTURE, in contrast, indicates some populations in the invaded region cluster differently than most individuals in the region. Principal component analyses, Mantel test for isolation-bydistance, distance matrices (Nei/FST), and diversity statistics (allelic richness, observed heterozygosity, FIS) favor STRUCTURE’s results. Evidence suggests that the southwestern U.S native range and the invaded California range have similar genetic diversity and population structure for this weedy species.