What are the places where betting is allowed in US?

It'snot "everywhere." I don't know the exact answer offhand, but there are plenty of states where any kind of gambling is illegal. I live in one of them -- Hawaii. We can't even buy a Megabucks ticket here. That's why Hawaiians spend all their hard-earned money flying to Last Vegas to gamble. The Honolulu-t0-Vegas route is practically an hourly shuttle.

Why is sports betting that popular in the USA, you ask. I don't know how to answer that. All I can think of is, why wouldn't it be?

Thanks Andrei, This is a good answer. I have no cross questions.