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Across the world, grassland declines over the last century have coincided with the declines of many grass-feeding butterflies, and the Carson wandering skipperPseudocopaeodes eunus obscurus(CWS) is one such taxon. The CWS is a federally endangered subspecies of grass skipper butterfly with only 3 remaining populations on the western edge of the Great Basin Desert, in Nevada and California, USA. Since its federal listing under the Endangered Species Act in 2001, it has been monitored annually but has not been the subject of intensive research. To improve our understanding of the CWS, we used count data from surveys over the last several decades to assess CWS population status. In addition, to better understand and characterize current habitat for the CWS, we collected vegetation data from 2021-2022 in areas that are currently occupied by the subspecies, and in areas that have no record of CWS occupancy but otherwise met some or all criteria for suitable habitat. We found that the CWS is in decline and that its habitat is characterized by low to moderate densities of saltgrassDistichlis spicata, the larval host, and the presence of alkaline- or salt-associated nectar resources as well as other saltgrass community associates. We discuss the possibility that the remaining occupied habitat is not necessarily optimal habitat. We also discuss the implications of our status assessment of the CWS for other butterfly taxa with severely restricted ranges in the arid western USA.