Objectives. To explore US geographic areas with limited access to HIV preexposure prophylaxis (PrEP) providers, PrEP deserts.Methods. We sourced publicly listed PrEP providers from a national database of PrEP providers from 2017 and obtained county-level urbanicity classification and population estimates of men who have sex with men (MSM) from public data. We calculated travel time from census tract to the nearest provider. We classified a census tract as a PrEP desert if 1-way driving time was greater than 30 or 60 minutes.Results. One in 8 PrEP-eligible MSM (108 758/844 574; 13%) lived in 30-minute-drive deserts, and a sizable minority lived in 60-minute-drive deserts (38 804/844 574; 5%). Location in the South and lower urbanicity were strongly associated with increased odds of PrEP desert status.Conclusions. A substantial number of persons at high risk for HIV transmission live in locations with no nearby PrEP provider. Rural and Southern areas are disproportionately affected.Public Health Implications. For maximum implementation effectiveness of PrEP, geography should not determine access. Programs to train clinicians, expand venues for PrEP care, and provide telemedicine services are needed.