Back in the spring, when the World Cup was just a few weeks away from descending on the New York region, there was real concern in the hospitality industry that no one would come. The host committee’s prediction of a multibillion dollar financial windfall seemed a stretch. Vijay Dandapani, the president of the Hotel Association of New York City, was skeptical of the bold predictions."It’s not like the U.S. Open," he said at the time. "That’s an economic machine every year."The World Cup, which came to the region for only the second time in its 96-year history (with games played in New Jersey, not New York City), ended up providing a bit more of an economic boost than Mr. Dandapani originally expected.

But in a follow-up conversation this month, he said he still sees the U.S. Open as a far more reliable driver of economic activity."This is far and away the best sporting event the city has," Mr. Dandapani said earlier this month. "In fact," he added, "the country has, in a concentrated period of time."So, how much money does the U.S. Open bring to New York City? The figure that has been tossed around most frequently over the last few years is $1.2 billion annually. The number comes from a study commissioned by the United States Tennis Association, which runs the U.S. Open out of the Billie Jean King National Tennis Center in Flushing, Queens and has an interest in demonstrating its financial value to the city, especially since the tournament sits on parkland owned by New York City. Assuming all the figures are accurate (which is open to interpretation — the $1.2 billion might actually be low) the U.S. Open produces every three years what the World Cup does once in a generation. (The World Cup’s New Jersey and New York host committee recently upgraded its projected impact to $3.5 billion for the entire area).

But tennis is every year. With its unique combination of high-end clientele and huge attendance — a record 1.14 million fans went last year — the U.S. Open boasts both the aristocratic spending power of a polo match with the populist volume of an N. F.

L. franchise. In fact, the tournament generates almost double the attendance of the average football team. The U.S. Open had virtually the same number of fans last year (a mere 8,000 fewer) than both the Giants and Jets had combined over 17 football games at Met Life Stadium.

And the U.S. Open gets a lot more out-of-town visitors, who provide the fuel that drives a city’s economic engine the fastest: New money, or cash brought in from out outside the city and spent there. Based on its own customer surveys, the U.S.T. A. estimates that 43 percent of U.S. Open visitors come from outside the New York area, including 8 percent from other countries.

Many travel experts agree that international travelers stay longer and spend up to four times more than domestic travelers. According to John Neill, director of an advisory group for the consulting firm the U.S.T. A. paid to analyze the economic impact of the U.S. Open, the $1.2 billion could even be an undercount."On a year over year basis, it’s a major economic driver for New York City," Mr. Neill said.

For the study, his firm, AKRF, measured things like visitor spending, wages paid to workers and purchases from suppliers to track how money circulates through the economy. A visitor spends money on hotel, restaurants, local transportation, tickets and perhaps a few trinkets. The hotel and restaurant workers, the Uber driver and shop clerks then presumably spend some of that money in New York and the cycle continues.

The analysis was based on 2023 U.S. Open data and with attendance and revenue going up every year, Mr. Neill said it is likely that a new study would show an even higher figure. Some are skeptical of these kinds of projections. Andrew Zimbalist, a professor emeritus of economics at Smith College and an expert on the economics of sports, has not seen the study.

But he cautioned that there are ways to make data fit a narrative."It...