when did the nfl start the 2 minute warning
Two-minute warning The origins are from the early years in the NFL when the official game time was kept by a member of the officiating crew, with the stadium clock being unofficial. Its purpose was a checkpoint to ensure that the teams knew how much time remained in the game. In the early 1960's the upstart American Football League made the stadium clock the official game time, a change followed later in the decade by the NFL. By then, television was an important factor in professional football, so the two-minute warning was retained as a commercial break and to serve as "tension building" time, and thus has become an important part of the game's flow.[3]