The Hull-Rust-Mahoning Mine in Hibbing, Minnesota, is the largest open pit iron mine in the world. The mine, located in the Mesabi Range, supplied as much as one-fourth of all the iron ore mined in the United States during its peak production years of World War I and World War II. This area of the Mesabi Range was explored in 1893-1894, shortly after the Mountain Iron mine was established in 1892. The early development was as an underground mine, but open cast mining soon proved to be a better choice because of the soft, shallow ore deposits. Many open pits in the area soon merged into one large mine, and the consolidation of mines led to the formation of U.S. Steel in 1901. The growth of the mine even resulted in the town of Hibbing being relocated to accommodate expansion.