Spokane serves as the major hub for the Inland Northwest, particularly for service industries, wholesale and retail trade, medical industries, education, and entertainment. Productive industries have included construction and mining, manufacturing, transportation, communication and networking utilities, finance, insurance, real estate, health care, and government. Forests in the surrounding areas are responsible for one-quarter of the world's white pine trees. There are almost 30 million acres of profitable forests in the Spokane exchange.