This marks the third weekend of play for the Alliance of American Football, and so far a lot of fans have tuned in on TV, but the AAF acknowledges it has a long ways to go.

The AAF is not in competition with the National Football League and in fact identifies itself somewhat as a developmental league for the NFL.

Since there is no true minor league system beneath NFL play, that seems like a good concept. The league could provide work for a lot of young players who have been cut from NFL teams and give them rungs of a ladder to perhaps climb their way back.

But while the Alliance is new, the concept of new leagues in pro football is not.

By my math, the AAF is at least the 14th league to play American football, in addition to a large number of actual minor and semi-pro leagues.

Some of those leagues were not in business long enough to document, but some gave it a long try before being forced by finances to cash out their chips — or what few chips they had remaining.

This is the 100th year anniversary of the NFL, and many fans know that this is also the 60th anniversary of the Denver Broncos and the American Football League.

The AFL never failed — in fact it was so successful that it forced a merger with the NFL, and in that merger the AFL became the only sports league in American history to have every one of its franchises be absorbed by and continue to play in the larger league.

Of the 32 NFL franchises today, 10 were original AFL members, including the Broncos.

The AFL that we know and love played from 1960-69, but that was not the only AFL.

In fact, there were three American Football Leagues before the most recent.

The first AFL played only in 1926, and there were teams in nine cities with franchises ranging from the New York Yankees to the Chicago Bulls to the Los Angeles Wildcats — who were actually based in Chicago. That league folded after just one year, with the Yankees actually being absorbed into the NFL.

The second AFL played for two years, 1936-37, and this time there were six teams that challenged the NFL.

Once again there was a New York Yankees franchise, but the league also included the Cleveland Rams, the predecessor to today's Los Angeles Rams. The Rams actually went from Cleveland to Los Angeles to St. Louis, before going back to Los Angeles as the current franchise.

Other teams included the Los Angeles Bulldogs, who actually did play in Los Angeles, as well as the Boston Shamrocks. In 1936, the Shamrocks actually outdrew the NFL's Boston Redskins, leading Redskins owner George Preston Marshall to relocated his Boston franchise to Washington, D.C.

But again, there was no television then and the AFL ran out of money and folded.

But in 1940, a third AFL was formed (besides the NFL, the moniker "AFL" was just too logical and kept coming back), with this league again playing for two seasons, 1940 and 1941.

This time there were five franchises, including — you guessed it — the New York Yankees, but the onset of World War II and the resulting military draft dried up the source of players for all of pro football and the new league just did not have enough resources to continue.

The Pacific Coast Professional Football League also formed in 1940, and it was notable because it was the first league on the West Coast. They actually managed to stay in business through the war before folding in 1948.

In an effort to be merciful to the reader, I have skipped and will skip a number of leagues that one can only call fly-by-night, to be kind, but they appeared like vapors and disappeared from the sporting scene just as fast.

The one other league that preceded the successful AFL of the 1960s and had surviving franchises was the All-American Football Conference.

Do not be deceived by the word "Conference."

The AAFC was professional in every way, competed with the NFL and existed from 1946-49.

This one was real.

It attracted some of the nation's best players and posed a serious threat to the NFL.

The league was dominated by the Cleveland Browns, who were so good that Cleveland Rams Hall of Fame owner Dan Reeves (no relation to our former coach) moved his team to Los Angeles because he felt he could not compete with the Browns for fans.

In fact, the Rams moved despite having won the NFL title the previous season, and they remain the only major American franchise in any sport to relocate immediately following a world championship campaign.

The Browns made a huge impact on pro football on and off the field, both in practice and film study regimens and as the first modern professional football team to sign black players.

But increasing costs led to the AAFC inevitably folding following the 1949 season, and the Browns joined the Baltimore Colts and San Francisco 49ers in the NFL.

The Colts have had a nomadic history, but that is a matter for another time.

Fans may be familiar with the ill-fated United States Football League (1983-85), which tried to compete with the NFL, and with Arena Football League, which did not. The Arena League started in 1987 and continues as an indoor league with its own fandom today.

Minor leagues and semi-pro leagues?

Too many to seriously factor in, and they have existed in all regions of the country and in some cases have not even been able to play full seasons.

The Alliance of American Football is on television — always a big plus — and views itself (and is viewed) as developmental rather than competitive in nature. That is a big deal, as the NFL is not only the most successful sports league in American history but is just too big to topple in direct competition for pro football fans.

So we wish the AAF well and will continue to watch games, with the knowledge that they are the latest but not the only other pro football league to dot our sports landscape.