The AMA's youngest age class is Pee Wee Jr., which is a 50cc class, ages 4-6.
Motorcross is competed in, all around the world, at various motorcross tracks
300cc
Motorcross is popular EVERYWHERE but mostly i would say America and the UK
Well, you don't 'play' motorcross! You ride it, and you do this at any outdoor or indoor tracks.
Probably motorcross because if a 3 year old child can cycle then that's enough proof for that.
In the 1800s
British
no
well it depends on who but football players at an average do make more $ than motorcross bikers.
falling down and death
about 70mph
No, but thanks for asking.