In the early 1960s, rising coal demand from Muskingum River Power Plant led to the creation of Big Muskie, a Bucyrus-Erie 4250-W dragline that became the largest walking dragline ever built and the biggest machine ever to move on land. It took about two years to fabricate and another two years to assemble on site, then began coal production in May 1969. Enormous in scale, it had a 310-foot boom, a house that revolved on a 105-foot-diameter tub, and a 220-cubic-yard bucket capable of taking 325 tons of earth in a single bite. During its operating life, Big Muskie moved more than 483 million cubic yards of material to uncover nearly 18 million tons of coal, working where smaller machines could not reach the full 180-foot depth needed to expose the Meigs Creek No. 9 coal seam. When it shifted from one area to another, its 151-foot width required a road wider than an eight-lane highway and with less than a 5 percent grade. Its immense size was also a weakness, because its huge tub needed a flat, level, stable surface to support its 14,000-ton working weight, and its walking mechanism lifted the entire tub off the ground, preventing it from operating on cast-blasted material. Big Muskie was idled in January 1991 as more efficient mining technologies and reduced demand for the mine's high-sulfur coal after the Clean Air Act Amendments of 1990 removed the need for it. It stood unused for eight years before AEP announced in January 1999 that efforts to preserve it had failed, after which it was dismantled beginning in February 1999 and the site was reclaimed, leaving only its huge bucket.