We assessed the effect of campgrounds on American crow (Corvus brachyrhynchos) populations on the Olympic Peninsula in Washington, USA, because crows are potential nest predators for marbled murrelets (Brachyramphus marmoratus). We measured resource use, home range, relative abundance, and reproduction for 39 crows in 13 campgrounds that varied in size and proximity to other sources of anthropogenic food. Campgrounds concentrated crow populations and individual resource use. However, campgrounds did not provide optimal conditions for reproduction. Instead, reproduction was highest for crows that accessed exurban areas surrounding campgrounds. Concentration of use in exurban lands by 6 crows that nested >5 km from camprounds or human settlements confirmed the far-reaching effects of human activity in this area on crows. We concluded that human settlements fueled crow population growth on the Olympic Peninsula, and remote campgrounds absorbed this growth through colonization. As exurban crow populations expand, campgrounds likely will experience increases in local abundance of crows. Our observations do not suggest that rising crow populations will reduce the nesting success of other birds near campgrounds, but crows may indicate the suitability of campgrounds to other human commensals. Managing food resources within campgrounds may be insufficient to curtail crow population growth. Instead, regional cooperation is needed to identify and reduce food sources at broad spatial scales to target source populations.