BILLINGS, Mont. (AP) — U.S. wildlife officials are proposing to remove federal protections for grizzly bears in and around Yellowstone National Park. Here's a look at some significant events leading to Thursday's proposal:

1890 to 1940s: Yellowstone National Park visitors are entertained by nightly "bear shows" at garbage dumps frequented by grizzlies seeking easy meals.

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1970: Last of park's garbage dumps closes, largely to end visits by bears that were becoming habituated to humans and threatening visitor safety.

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1975: Grizzly bears across the Lower 48 states are protected under the Endangered Species Act after widespread extermination; Yellowstone population is estimated at 136 bears.

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1993: U.S. Fish and Wildlife Service adopts grizzly bear recovery plan.

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2007: Yellowstone grizzlies are removed from the threatened species list.

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2009: U.S. District Judge Donald Molloy orders bears back onto the protected list, citing potential threats to their food supplies due in part to climate change.

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2011: Two hikers are killed by grizzlies in separate attacks, the first bear-caused human fatalities in Yellowstone in almost 25 years.

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2013: Government scientists recommend lifting bears' protected status, citing studies that show the animals can adapt to changes in food supply.

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2015: An estimated 717 bears live in the 19,200-square-mile Yellowstone region.

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2016: The U.S. Fish and Wildlife Service proposes to again remove the animals from the threatened list.