Magnetic taconite is part of Minnesota's iron formation and is in many ways similar to other iron-bearing materials found in the United States and throughout the world. Forty years of work in mining firms' laboratories and at the University of Minnesota developed methods for processing taconite's meager iron content into a competitive iron ore product. Taconite processing plants brought new jobs for miners and new opportunities for those who supply or serve them. On November 3, 1964, Minnesota voters endorsed the principle of fair tax treatment for the huge investments a taconite plant entails, and mining companies responded by starting construction of new facilities expected to expand taconite job-producing investments to exceed a billion dollars, the largest new industrial investment in the state. One of Minnesota's new taconite plants was to be located at Mountain Iron, where Lon Merritt and his six iron men established the Mesabi's first mine in 1890 and opened the area to development. The Merritts gave mining on the Mesabi its birth seventy-five years earlier, and taconite offered Mountain Iron and the Mesabi a rebirth as major iron ore suppliers to an America still building.