Golf is more popular than tennis in the USA for sure, but worldwide I doubt it.
That may be, but the growing strength in European players shows golf is gaining in popularity there as well. And I'm concerned with golf in America, and how we regain an edge in world standings. Great golf, regardless of where it comes from, is good for the game, but I'll root for the home team every time. And I want to see that home team as strong and contentious as it can be. Nothing wrong with that.
I just Googled it and Tennis is #3 or #4 in terms of world popularity, behind soccer, cricket and rugby. In fact basketball is probably more popular worldwide than golf is.