I think Skateboarding is more popular.
Skateboarding is getting more and more popular everyday so the answer is today
Skateboarding is popular in most countries. That's why they have different contests for world-wide skaters. Skateboarding is most popular in the United States. Specifically, Skateboarding is most popular in California. California has many skateboading parks and lots of skateboarding stores. If you wanted to skateboard I would recommend California.
Both - skateboarding is popular with children, and so too are skateboarding competitions.
Baseball is more popular.
Baseball. It's Americas sport although skateboarding is one of the most popular extreme sports
Basketball is a more widely played sport but I guess its whoever you talk to Skateboarding is much more popular than basketball because I ask people what is your favorite sport between basketball or skateboarding and they say skateboarding.