WHITE PINE, Mich. (AP) — A mining industry that's been in serious decline for decades in the Upper Midwest is poised for a comeback. Mining for iron ore and copper was an economic pillar in Michigan, Minnesota and Wisconsin a century and more ago. But it fell onto hard times as production shifted elsewhere and prices declined. Now, rising demand in the U.S. and China has spurred more exploration. At least six open-pit or underground metal mines have been proposed or started in the three states. No one expects a return to the industry's heyday, but the new mines could provide an economic boost in rural areas hungry for jobs. Some worry about the industry's boom-and-bust history and environmental damages. Companies say they've learned from past mistakes and will leave a smaller footprint.