The National Football League does not have a minor league system as of 2011 .
National Football League has operated or affiliated with minor leagues in the 1930s , 1940s , 1960s , 1990s , and the early 2000s and invested in another in the late 2000s .
The National Football League does not have a minor league system as of 2011 but it has operated or affiliated with minor leagues in the 1930s , 1940s , 1960s , 1990s , and the early 2000s and invested in another in the late 2000s .