With $9.3 billion in annual revenue, the NFL could afford to buy the Minnesota Vikings a stadium.

When Sports Illustrated crunched the numbers in March 2011, it estimated that the NFL is a $9.3 billion-a-year enterprise. That’s almost as much money as flows to Major League Baseball, the NBA, and the NHL combined.

About half of the NFL’s money comes from media rights (broadcast, cable, etc.). One company, Nike, pays the league $1.1 billion a year for sponsorship rights, and that’s only one league sponsor.

Sports Illustrated doesn’t provide a detailed breakdown of league revenue sources, but it’s clear from what the publication does provide that the league lives pretty well even before stadium revenue is considered. That in turn prompts a question: Shouldn’t the league buy stadiums for its teams?┬áIt has the money to do so, and a stadium (or at least a field) is an essential input to the football factory.

In a sidebar to its article, SI even offers up some examples of privately financed stadiums. It reports that the New Meadowlands stadium (New York Jets, New York Giants), which cost $1.6 billion, was 100 percent financed by private money. The same for Gillette Stadium (New England Patriots).

A quick analysis of the list suggests that the larger the city, the larger the private-sector contribution. (For example, Philadelphia: 65 percent; Indianapolis, 13 percent.) That makes sense; there’s more “local” money available for sponsorship and naming rights as the metropolitan area gets bigger. But the giants (and Giants) have to play small market teams in Indianapolis and Minneapolis, so it’s reasonable to argue that the league ought to finance stadiums to support all teams.