Can someone explain this to me???? It's about sports?

I've been watching foreign sports games since 2008, but I never could understand this: Why do Canadian teams play in American leagues? Like the following teams: Toronto Raptors (NBA) Toronto Blue Jays (MLB) Montreal Impact (MLS) Toronto FC (MLS) Vancouver Whitecaps (MLS) Montreal Canadiens (NHL) Ottawa Senators (NHL) Toronto Maple Leafs (NHL) Winnipeg Jets (NHL) Calgary Flames (NHL) Edmonton Oilers (NHL) Vancouver Canucks (NHL) Why Canada doesn't create it's own leagues? Before you ask, I'm not Canadian nor American, sorry for my ignorance