Many governments maintain lists of species of conservation concern (SCC), and jurisdictions at the peripheries of species' ranges can help prevent declines of species that are common range-wide by protecting peripheral populations. However, patterns in the sizes of jurisdictions may bias where common species are likely to be protected at their periphery. We used simulations of hypothetical species ranges to determine whether the geographic pattern in sizes of U.S. states has the potential to

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... s the proportion of anurans listed as species of concern at the state level. Then, we investigated whether the bias found in the simulations was evident as a bias in state listing decisions. The distribution of states resulted in a pattern of more peripheral occurrences (< 10% of a species' range occurring within a state) predicted in the eastern states than central or western states when range size was small to medium and more in the central states than eastern or western states when range size was large. Despite this pattern, species were more likely to be both listed as SCC and peripheral in the western states, and this is not sufficiently explained by higher risk of extinction in the west (estimated as the percentage of state species listed as federally threatened or endangered). Thus, despite being predicted to have fewer peripheral occurrences because of their large size, western states list a higher proportion of peripheral species than central and eastern states. Similar patterns in the sizes of political units elsewhere could bias our global preparedness to detect shifting ranges of both anurans and other species and to respond to those shifts in the face of climate change.