A coalfield is an area of certain uniform characteristics where coal is mined. The criteria for determining the approximate boundary of a coalfield are geographical and cultural, in addition to geological. A coalfield often groups the seams of coal, railroad companies, cultural groups, and watersheds and other geographical considerations. At one time the coalfield designation was an important category in business and industrial discussions. The terminology declined into unimportance as the 20th century progressed, and was probably only referred to by a few small railroads and history buffs by the 1980s. Renewed interest in industrial heritage and coal mining history has brought the old names of the coalfields before a larger audience.