In 1906, Kooi Peter Kooi established the Kooi Mine, the only area coal mine founded by an individual rather than a company, and soon organized a modern mining camp where he promoted a band, baseball team, parades, and holiday celebrations that helped create strong community ties. The mine closed in 1922 and the school in 1955-56, and many houses were sold in the 1930s, moved off site, and reused. Coal forms from plant material that accumulates as peat, is broken down by bacteria into a dark gel, and over millions of years is pushed underground, compressed, and heated into solid coal. More than half of Wyoming contains coal reserves, and Powder River Basin coal, with its low sulfur content when burned, is the type of coal most in demand. The Powder River Basin is the largest coal-producing region in the U.S., one of the richest coal deposits in the world, and in 2012 supplied about 40 percent of the nation's coal.