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As human development spreads ever farther around the world, very few large ecosystems remain relatively intact and uninterrupted by highways, cities or other human-constructed obstacles. One of the largest exceptions is the Yellowstone to Yukon region, or Y2Y, which stretches more than 2,000 miles (3,200 kilometers) northwest from Wyoming into Canada's Yukon territory. For the past 30 years conservationists have worked to knit this huge stretch of land together under the Yellowstone to Yukon Conservation Initiative.
