With the Masters' first-ever November start just three days away, it's a great time to look back on 2020's golf boom.Why it matters: Golf was a physical and mental safe haven for millions of Americans with cabin fever this year, and even moderate retention of the sport's newcomers could help buoy an entire industry for years to come.By the numbers:More rounds: September saw a 25.5% increase in the number of rounds played year-over-year — the fifth straight month to surpass last year's totals.More sales: Equipment sales increased 42% year-over-year in the third quarter to just over $1 billion. It was the industry's second-best quarter ever.The backdrop: When everything shut down in March, major golf organizations formed Back2Golf and began lobbying governors to allow courses to reopen.By May, they'd worked with the CDC to devise return-to-play guidelines for the socially-distant sport (i.e. no rakes in bunkers, raised cups).In June, the PGA Tour became one of the first professional sports to resume in the U.S.The big picture: This boom was great for the golf industry in a year when so many businesses were lucky to even tread water, but it should also help grow the sport beyond the pandemic's lifespan.The National Golf Foundation estimates the number of junior golfers could increase by 20% (500,000) by year's end, and new or lapsed golfers also increased 20% in H1, per WashPost.