Shortleaf pine varies greatly in the quality and amount of sapwood. It is normally a thick sap tree, but midway between loblolly and longleaf. The young tree increases rapidly in size until it is from six to ten inches in diameter, and the yearly rings are wide. The rate of growth then decreases and during the rest of its life the rings are narrow. This feature is often of assistance in identifying southern yellow pine logs or large timbers which contain the heart and also the sap. Wide rings near the heart, followed by narrow ones, and a thick sapwood are pretty good evidence that the timber--if a southern yellow pine--is shortleaf pine. The rule is not absolute; for a high authority on timber has said that no infallible rule can be laid down for distinguishing by sight alone the woods of the four southern yellow pines--longleaf, shortleaf, Cuban, and loblolly. The wood of shortleaf pine is strong, heavy, hard, and compact; very resinous, resin passages large and numerous; medullary rays numerous, conspicuous; color, orange, the sapwood nearly white. The thoroughly seasoned wood weighs thirty-eight pounds per cubic foot. It is about five pounds heavier than loblolly pine, five pounds lighter than longleaf, and nearly nine pounds lighter than Cuban pine. There is so great a variation in weight of shortleaf pine that only general averages have value. Shortleaf pine is not as strong as longleaf, and is not so extensively employed in heavy structural work, but in certain other lines it has the advantage of longleaf. It is softer, and door and sash makers like it better. It is easier to work, and when manufactured into doors and interior finish many consider it superior to longleaf. The wide rings of annual growth in the heartwood show fine contrast in color, and when these are developed by stains and fillers, the grain or figure of the wood is very pleasing. Where hardness is not an essential, it is much used for floors. It is in great demand by builders of freight cars, but less for frames and heavy beams than for siding and decking. Car builders in Illinois bought 77,000,000 feet of it in 1909. That was nearly half of the entire quantity of this wood used in the state. The second largest users in Illinois were manufacturers of sash, doors, blinds, and general millwork. If the whole country is considered, this is probably the largest use of the wood. Makers of boxes and crates in the South employ large quantities.