A wood product in which thin sheets of wood are glued together, grains of adjacent sheets being at right angles to each other in the principal plane. Because of this cross-grained orientation, mechanical properties are less directional than those of natural lumber and more dimensionally stable. Originally developed to replace wide wood boards that had been sawed directly from large logs, plywood was manufactured from logs not suitable for other purposes. It has since found such widespread use that tree farms are now cultivated specifically to yield logs suitable for processing into sheets for plywood. The softwood plywood capacity in the United States in 1997 was 12.5 million cubic meters. Southern pine represents the largest segment of this market.