For species with geographically restricted distributions, the impacts of habitat loss and fragmentation on long-term persistence may be particularly pronounced. We examined the genetic structure of Panama City crayfish (PCC), Procambarus econfinae, whose historical distribution is limited to an area approximately 145 km2, largely within the limits of Panama City and eastern Bay County, Florida, USA. Currently, PCC occupy approximately twenty-eight percent of its historical range, with suitable habitat composed of fragmented patches in the highly urbanized western portion of the range and managed plantations in the more contiguous eastern portion of the range. We used 1,640 anonymous single nucleotide polymorphisms to evaluate the effects of anthropogenic habitat modification on the genetic diversity and population structure of 161 PCC sampled from across it known distribution. First, we examined the urban habitat patches in the west compared to less-developed habitat patches in the east. Second, we used Approximate Bayesian Computation to model inferences on the demographic history of eastern and western populations. We found anthropogenic habitat modifications explain the genetic structure of PCC range-wide. Clustering analyses revealed significant genetic structure between and within eastern and western regions. Estimates of divergence between east and west were consistent with urban growth in the mid-20th Century. PCC have low genetic diversity and high levels of inbreeding and relatedness, indicating populations are small and isolated. Our results suggest that PCC have been strongly affected by habitat loss and fragmentation and management strategies, including legal protection, translocations, or reintroductions, may be necessary to ensure long-term persistence.