If there are two, one is Toronto Pearson International Airport (YYZ) is roughly an hour and a half and the other is Hamilton International Airport (YHM) - that is roughly an hour
In case you come from the American side, the Buffalo airport is closer, about 30 minutes. ;)
If you come from the American side, don't you have to cross the border to see the falls?
Thanks! Your answer is awaiting moderation.