The purpose of this study was to further characterize a distinct population of Greater Sage-grouse: the population located along the border between Nevada and California (Bi-State Planning Area) and centered around the Mono Basin. This population was previously determined to be genetically distinct from other Greater Sage-grouse populations across their range. Previous genetic work focused on characterizing genetic variation across the species' range and thereby used a coarse sampling approach for species characterization. The goal of this study was to investigate this population further by obtaining samples from breeding locations within the population and analyzing those samples with the same mitochondrial and microsatellite loci used in previous studies. Blood samples were collected in six locations within the Bi-State Planning Area. Genetic data from subpopulations were then compared with each other and also with two populations outside of the Bi-State Planning Area. Particular attention was paid to subpopulation boundaries and internal dynamics by drawing comparisons among particular regions within the Bi-State Planning Area and regions proximal to it. All newly sampled subpopulations contained mitochondrial haplotypes and allele frequencies that were consistent with the genetically unique Bi-State (Mono Basin) Greater Sage-grouse described previously. This reinforces the fact that this group of Greater Sage-grouse is genetically unique and warrants special attention. Maintaining the genetic integrity of this population could protect the evolutionary potential of this population of Greater Sage-grouse. Additionally, the White Mountains subpopulation was found to be significantly distinct from all other Bi-State subpopulations.