Falling temperatures, leaves changing color and shorter days are all harbingers of one important annual occurrence: Football season is starting. 

The upcoming NFL and NCAA college football seasons have a special significance for casino operators this year following the U.S. Supreme Court's ruling that states have the right to self-determine whether they want to allow sports betting.

Caesars Entertainment Corp.  (CZR) - Get Report launched sports betting at its Horseshoe Tunica Hotel & Casino on Aug. 14, while also launching sports betting at Harrah's Gulf Coast Hotel & Casino in Biloxi, Mississippi on Aug. 20. MGM Resorts International  (MGM) - Get Report was the first to market in Mississippi, launching sports books at the Beau Rivage Resort & Casino and the Gold Strike Casino on Aug. 1. 

However, sports books traditionally have slimmer margins than traditional games like slots, so being early to the party is necessary for any company looking to make money off of these new sports betting opportunities, according to Union Gaming analyst John DeCree.

"Sports betting will have a very large market in the U.S. Early reports out of (New) Jersey have been encouraging," DeCree told TheStreet. "Being a first mover is a big advantage, especially for digital betting. Margins are thinner, so it is important to have a larger market share."

The push into gaming is part of Caesar's long-term growth plan, according to CEO Mark Frissora.

"Caesars Entertainment is pursuing a robust agenda of domestic and international growth," Frissora told TheStreet. "We are optimistic about the prospects for our domestic business and are continuing to focus on executing with discipline and adding new offerings, including sports betting, which launched this month in New Jersey and Mississippi and we continue to expand as additional jurisdictions present that opportunity." 

So far, New Jersey, Delaware and Mississippi are the only states outside of Nevada to launch fully legal sports betting since the court's ruling and gaming companies with an eye toward the future already have begun their push into what could be a potential $500 billion market, according to the American Gaming Association. 

Meanwhile, another four states -- New York, Pennsylvania, West Virginia and Rhode Island -- have passed bills that have not been implemented, and another 14 states have introduced bills that have not yet passed, according to ESPN.  

Football is just the beginning, however. 

While football is the most widely consumed sports betting opportunity every week, there is only one day of betting. Pro basketball is wagered on far more often than football is, according to Sarah Slane, senior vice President of public affairs for the American Gaming Association.