Playing the Game-United States football
is played by 11-man teams on a field100 yards long and 160 feet wide with
lines at 5-yard intervals along the 100-yard axis. An end zone extends
10 yards behind each goal line. Parallel to the sidelines are two broken
lines that designate where the ball is placed after it has been carried
out of bounds. In college football these hash marks are 53 feet 4 inches
from each sideline; in professional games the distance from the sidelines
is 70 feet 9 inches. The goalposts in high school and college football
have different dimensions from those in the
professional
game. At all three levels, the goalposts are placed 10 yards behind the
goal lines and the crossbar is 10 feet above the ground. In professional
football, however, the width between the posts is 18 feet 6 inches, and
the width in high school and college is 23 feet 4 inches. The uprights
of the goalposts in professional football extend 30 feet above the crossbar;
in high school and college the uprights must be at least 20 feet in all.
A football is oval with a rubber bladder inside what is usually a leather
cover. Some footballs have a rubber or plastic cover. A football weighs
14 to 15 ounces and has an air pressure of 12 1/2 to 13 1/2 pounds per
square inch. It is 10 7/8 to 11 7/16 inches long and measures 20 3/4 to
21 1/4 inches around the middle.