The National Football League (NFL) was formed in out of the American Professional Football Association The Dallas Cowboys joined the NFL in as an expansion team. . I bet no one knows the cardinals is the oldest team. Reply. The two teams with the oldest projected offensive starters (Broncos, Patriots) are probably the two of the NFL's best teams, but you'll also find a. The legendary year old Penn State Football coach has called the plays in . sharing between teams, a concept that has made the NFL the most powerful.