The United States uses large quantities of natural aggregate to build and maintain a continuously expanding infrastructure. In recent years, per capita demand for aggregate in the United States has grown to about 9.7 metric tons (10.7 tons) per person per year. Over the next 25 years, the aggregate industry expects to mine quantities equivalent to all aggregate mined in the United States over the past 100 years. The issues surrounding supply and demand for aggregate in the mid-Atlantic states of Maryland, Pennsylvania, Virginia, and West Virginia illustrate competing requirements for industrial minerals and many simultaneous social and environmental objectives.