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The number of grizzly bears (Ursus arctos) and the size of their former range within the western states (USA) have declined drastically over the previous 200 years. The downward trend has continued most sharply in the Greater Yellowstone Ecosystem, accelerated by the closing of open-pit garbage dumps in the late 1960s. The closure resulted in an estimated 50% reduction in population size. The immediate response by bears to the dump closures was significant movement into campgrounds and developed areas where many bears were captured and destroyed. Over a period of 15 years, the surviving bears moved out from aggregation centers (open-pit dumps, termed ecocenters) to exploit more fully the natural food base. The major detectable difference in resource use between pre- and post-closure periods was an especially heavy use of forbs. There was no evidence that the post-closure bear population found nutritional resources comparable to the ecocenters. Bears changed feeding habits and altered their distribution and use of space throughout the ecosystem. Recovery of a single grizzly bear population unit such as the Yellowstone population should be considered the first step in a multi-step recovery program for long-term persistence in the contiguous 48 states. Delisting of the Yellowstone population, if it occurs at all, must await population recovery throughout the Northern Rockies.