I'd have to say Soccer is the fastest growing sport. It used to be all the kids, (pretty much), played soccer very early in life but dropped out when they got older to play baseball, football, basketball. Today quite a few are staying with soccer.
Track and Field is making a comeback... and I couldn't be happier about that. Last year was my grandson's High School's first year back into Track since... I dunno, decades ago.
Our High School is starting a Water Polo team next year.... I love it. I have a relative who played on the women's Sydney Olympics water polo team.