Solid waste is composed of a broad array of materials discarded by households, businesses, industries, and agriculture. The United States generates more than 11 billion tons (10 billion metric tons) of solid waste each year. The waste is composed of 7.6 billion tons (6.9 billion metric) of industrial nonhazardous waste, 2–3 billion tons (1.8–2.7 billion metric) of oil and gas waste, over 1.4 billion tons (1.3 billion metric) of mining waste, and 195 million tons (177 billion metric) of municipal solid waste.

Not all solid waste is actually solid. Some semi-solid, liquid, and gaseous wastes are included in the definition of solid waste. The Resource Conservation and Recovery Act (RCRA) defines solid waste to include garbage, refuse, sludge from municipal sewage treatment plants, ash from solid waste incinerators, mining waste, waste from construction and demolition, and some hazardous wastes. Since the definition is so broad, it is worth considering what the act excludes from regulations concerning...