In only its second season of existence, the Major League Soccer team in Atlanta sold more than 1 million total tickets this year.

Atlanta United FC, which shares Mercedes-Benz Stadium with the Atlanta Falcons, set a single-season MLS attendance record last year of 48,200 attendees per game on average. This year, the team’s attendance rose to an average 55,000 fans per game and had eight games that topped 70,000 fans.

Apart from NFL teams, Atlanta United had the highest average attendance of any U.S. pro sports team. Its attendance puts it in the top 15 most-attended pro sports teams in the world, bigger than Manchester City or Paris Saint-Germain. The team also hosted this year’s MLS Cup in its own stadium—and won. It was a banner year for soccer in Atlanta.

But the story with MLS in 2018 is much bigger than Atlanta. MLS is certainly still a distant cousin to America’s “Big Four” pro sports leagues (NFL, MLB, NBA and NHL) by revenue and eyeballs, but it is no longer “small” by any definition. This year, the league’s total attendance was 9.05 million, up from 8.72 million the year before; the league’s average ticket revenue per game rose by 10% over last year to its highest level in the league’s 23-season history; and viewership for the MLS Cup on Fox was up 71% over the year before to its highest rating since 1997.

“Soccer is on the rise in our country,” says MLS Commissioner Don Garber. “Major League Soccer is driving a lot of that energy.”

All of the momentum makes MLS our 2018 Sports Business of the Year. It’s a title we gave to Fanatics last year, and Adidas in 2016. Read on for more about how MLS is finally catching on with mainstream American sports fans.

[Yahoo Finance’s overall Company of the Year for 2018 is Square.]

Just 10 years ago, Major League Soccer had 14 teams. Next season it will have 24, with Cincinnati debuting. New teams in Nashville (2020), Miami (2020), and Austin (2021) are all confirmed. The league will name its 28th club next year.

LAFC, the new team in Los Angeles that debuted this season with a star-studded ownership group that includes Will Ferrell, Magic Johnson, Mia Hamm and Nomar Garciaparra, sold out every game at the new Banc of California Stadium.

View photos MLS Commissioner Don Garber in Cincinnati, May 2018. (AP Photo, John Minchillo). More

MLS is expanding voraciously, and each new expansion team pays a $150 million expansion fee. Forbes estimates that the average team is worth $240 million, up nearly 8% over last year. (MLS does not share its revenue figures.) And thanks to the expansion fees, the value of Soccer United Marketing, the commercial arm of MLS, has soared. Forbes reports that when MLS owners bought back Providence Equity Partners’ 20% stake in SUM, it valued SUM at $2 billion.

Record attendance at games, record eyeballs for MLS Cup

Attention for the 2018 MLS Cup, the league’s championship game, is perhaps the strongest evidence of a rise in popularity this year. The game drew a record in-person crowd of 73,019 and record TV viewership of 1.56 million viewers on Fox, peaking at 2.06 million viewers.

As for ticket sales, secondary ticketing marketplace Tickpick says it saw a 42% rise in MLS ticket sales on its site. “This year in particular,” says CEO Brett Goldberg, “we have really seen a significant jump in demand for MLS games.”

View photos Graphic by David Foster/Yahoo Finance More