Or has it ever happened earlier? I think it won't be a successful experience.
With 3 countries hosting the World Cup it will be the first time, but we already had the 2002 World Cup in South Korea and Japan, and it was a success.
I believe it will be an excellent event, even more so for the three countries in question.
Why do you think it will not be successful?
In my opinion, a World Cup hosted in the United States, Canada, and Mexico makes perfect sense, and it was a great choice.
For 2030 we could have 4 South American countries (Uruguay, Argentina, Paraguay, and Chile) or Spain, Portugal, and Ukraine, which also makes perfect sense to me and will be great choices again.
What was not a good choice and was totally questionable was holding a World Cup in Russia followed by one in Qatar, the criteria made no sense at all.
What I mean by all this is that in the past these choices have been very questionable, but something seems to have improved within FIFA, hopefully.
I don't believe there can be corruption with the US confederations for example, since they led the previous investigations against FIFA and its former presidents.