Betting on sports represents a small fraction of that amount, though industry experts say the court ruling will most likely allow that to increase significantly. In Britain, where the sports market is far less diverse and where the population is about one-sixth as large as that of the United States, gamblers wagered some $20 billion for the year ending in March 2017.
Analysts estimate that gamblers in the United States wager as much as $150 billion each year illegally through bookies and offshore accounts, as well as through less formal wagers, such as office pools around the men’s N.C.A.A. basketball tournament. With so much on the table for the Indian tribes, the days since Monday’s Supreme Court ruling have been filled with jockeying and strategic planning, especially in the states where Indian casinos have exerted powerful influence over local economies, such as California and Mississippi, in addition to Connecticut.
In California, dozens of Indian-owned casinos generate close to $8 billion in annual revenue, the most of any state, giving the tribes enormous influence over the gambling industry. Ahead of the Supreme Court decision, Assemblyman Adam Gray introduced a bill to amend the California constitution, which gives Indian tribes exclusive rights to operate slot machines and other casino-style games. The tribes say those rights include sports betting.
Since legalizing sports betting in California will require amending the state constitution, lawmakers, lobbyists and tribal leaders are now girding for a drawn-out, perhaps yearslong fight before anyone in the state makes a legal bet on a sporting event.
The tribal leaders base their claims to exclusivity on language in the state constitution that gives them the rights to games that involve “banking” — meaning the house creates the market for the bet.
In a statement this week, Steve Stallings, chairman of the California Nations Indian Gaming Association, formally requested a role in all negotiations over the future of sports betting.
“California voters have, on numerous occasions, confirmed the exclusive right of California tribal governments to operate casino-style games,” Mr. Stallings said. “Legalization of sports betting should not become a backdoor way to infringe upon exclusivity.”