Distributions of some plants and animals have already shifted in recent years due to climate warming, and climate warming has potential to extirpate populations of taxa that cannot easily move or adapt to changes in temperatures and/or moisture. This study in Pennsylvania, U.S.A. focuses on whether snail populations currently confined to cooler habitats at higher elevations (elevations 700–978 m comprise only 2% of Pennsylvania's area) might decline or be eliminated if their ranges are reduced upward by climate warming. We examined whether some land snail species are limited to upper elevations in order to assess whether climate warming poses a threat to them. Sampling included 108 sites across Pennsylvania, comprising 12 localities at each of nine elevations from 100 to 900 m elev. Overall numbers of snail species and abundances decreased at greater elevations. Most individual species tended to occur throughout sampled elevations or occurred primarily at lower elevations, so the reduced altitudinal range aspect of climate warming might not threaten them. However, five species occurred significantly more often at greater elevations suggesting that their populations might decline if climate warming were to reduce their ranges upward. Four additional species including three native slugs showed non-significant trends to occur at higher elevations. These species might be monitored into the future.