But the industry says counting on the US remains a risky bet, as UK companies face complicated state-by-state regulation and competition from entrenched local interests. "It's something that we're really focusing on, but equally we don't want to overhype it," said James Midmer, spokesman at Paddy Power Betfair, which recently purchased the US fantasy sports site FanDuel.
The US accounted for about 23% of the world's US$244 billion in gaming revenue last year, according to a report by Technavio published in January.
Recent US Supreme Court ruling found the law was an over-reach of federal power. But the court it did not actually legalise sports betting, leaving that question to local lawmakers.
That is expected to lead to significant variation in how firms get licensed, where sports betting can occur, and which events are open to speculation - with big implications for the size of the market.
Potential revenue ranges from US$4.2 billion to almost US$20 billion annually depending on factors like how many states move to legalise, Oxford Economics estimated in a 2017 study for the American Gaming Association.
Chris Grove, managing director at Eilers & Krejcik Gaming, predicts that 32 states will legalise sports betting in some form by 2023, creating a market with about US$6 billion in annual revenue.
But bookmakers face a far different landscape in America than they do in the UK, where betting shops are a frequent sight. US laws limited gambling largely to Native American lands and Nevada's Las Vegas strip until relatively recently.
As legalisation starts, sports betting firms are lobbying to fend off high tax rates, as well as requests by US sports leagues, which want to collect a percentage of revenue as an "integrity fee".
Analysts say UK firms will need to strike partnerships, offering their expertise and technology in order to make inroads. They point to SBTech's recent announcement that it is providing technology for Kentucky Derby operator Churchill Downs as an example of the kind of deals likely to materialise.
Joe Asher, chief executive at William Hill US, is clear-eyed about the realities. The company has been investing in the US market since 2011, when it purchased three US firms to establish a presence in Nevada.
William Hill now employs about 450 people in the US and has announced partnerships with casinos in Iowa and New Jersey. Asher said William Hill has become a household name in Nevada but that's not necessarily the goal everywhere.
"We certainly intend to have a very significant brand presence in New Jersey. In other states, it will just depend on regulation and potentially who our local partner is. The US is going to be the biggest sports betting market in the world. Obviously that's not going to happen on day one," Asher concluded.
Source: GMB / BBC
