The development of championship tennis players has, in the opinion of experts, been due as much as anything to the fast, uniform-texture surface of a concrete tennis court. The true, even surface assures a consistently accurate bounce of the ball, a feature essential to superior play. In northern latitudes, tennis courts are traditionally oriented with the long axis placed in a north-south direction and the net running in an east-west direction. The United States Tennis Association suggests that, south of the 42nd parallel of latitude, the long axis of the court be oriented 22 degrees counterclockwise of north to reduce the amount of direct sunlight in the players' eyes during prime playing time. Graded to the profile desired for the court, the subgrade should be uniform, hard and free from organic matter. If it is necessary to cut down trees in clearing the site, the roots should be removed so that subsequent decay will not cause settlement of the court. The site should also be cleared of all sod, humus, and other rich organic matter. Artificial drainage is provided to avoid pools of standing water, to reduce uneven frost heave and to afford fast surface drainage of the courts so that play can resume as quickly as possible after a downpour. Concrete tennis courts are constructed in various ways depending on the available funds and the contractor's construction preferences or for most installations is the continuously reinforced court. Having reinforcing bars throughout, it is joint-free in the playing area. The second type is the jointed court. It is reinforced with bars and has no joints while the remainder of the court has mesh reinforcement and control joints. A third type of concrete court is the prestressed court. It is built with prestressing steel strands pulled taut to put about 100 psi compressive stress in the concrete; this counters the tendency toward shrinkage cracking and provides a crack-free concrete playing surface.