As the frost clears and flowers begin to bloom, the “boys of summer” are back in business. Major League Baseball (MLB) is celebrating its 150th year and boasts more than 170 million fans in the U.S. and 10 million in Canada, according to Nielsen Sports Sponsorlink. MLB also had the highest average percentage of fans who’ve attended a game in 2018, according to Nielsen Scarborough research.

“One of the things that makes Major League Baseball very special is its accessibility to fans. Twenty-three percent of the U.S. adult population attended at least one game in their home market in 2018, compared to the 12% average across professional ‘stick and ball’ sports,” said Jon Stainer, Managing Director, Nielsen Sports Americas.

The average MLB team fan base is more than 2.5 million people. So it should come as no surprise that the top teams, based on the size of their local fan bases, are from some of the country’s most populated markets, including New York (Yankees and Mets), Los Angeles (Dodgers and Angels), Boston (Red Sox) and Philadelphia (Phillies). However, St. Louis, Kansas City, Cleveland, Houston and Pittsburgh can take pride in having the highest percentages of their local market populations as fans of their respective teams.

MLB is also gaining fans around the world, especially in Mexico and Japan, where the league is returning to host games in 2019. Interest in those countries’ age 16-69 populations is 42% and 24%, respectively, up from 39% and 22% in 2017, according to Nielsen SportsDNA, a global sports fan tracker. Interest in MLB in the U.K. has been steady for the past two years at 8%, and London will host Europe’s first ever MLB games on June 29th and 30th.

“The landmark two-game series at London’s iconic Olympic Stadium signals MLB’s strong intent to grow its brand internationally and create a footprint in the U.K. The limited participation base at a youth and grass-roots level in the U.K. highlights the difference in interest levels compared to Mexico and Japan; however, this summer’s series presents a great opportunity to drive interest in MLB,” said Stainer.

The league and its 30 teams provide a major platform for consumer brands to try to win the loyalty of baseball fans. In 2018, sponsors received a cumulative $2.4 billion in Quality Index (QI) Media Value from the televised game broadcasts. Banking, insurance, automotive and financial services topped all categories based on the value of exposure received.

The biggest shifts in sponsor category QI Media Value year-over-year included increases in exposure from websites, home improvement, beer, household products, insurance, soft drinks, banking and airlines. The sports drink category experienced the biggest year-over-year decrease, dropping 45% of its QI Media Value.

The exposure sponsors receive through MLB games is amplified through social media. According to Nielsen Sports Social24, brands sponsoring MLB teams experienced 3% to 13% of additional media value from their social media content. On television, the most visible sponsorship real estate appears on camera behind plate as a batter is ready to swing at a pitch, but the outfield actually gets more exposure via social media channels because big plays like home runs and acrobatic catches often make the highlight clips. MLB teams are playing catch up with NBA and NFL teams though. Some NFL teams tracked by Nielsen have driven as high as 75% share of media value. Likewise, in terms of total social media value, NBA team and league sponsors are on course to receive over $510 million.

MLB teams are using their social channels to score extra exposure for sponsors through branded content such as score updates, team quotes, starting line-ups, player stats, behind the scenes videos and player awards. A Nielsen Sports analysis shows teams with the largest number of social media followers are also the most active in posting sponsored content.

All 30 MLB teams will play on opening day (March 28).