Canton Fair is not an official name. The official name of Canton Fair is “China Import and Export Fair”, that is a big name.
It shows almost every thing. So that people do not know how to shorten it by product it shows.
It is not held in Beijing, the capital. Nor Shanghai, the biggist city in China. It is held in Guangzhou, which the new name of “Canton”. Most people still called this city “Canton” when the fair is startup.
So people just call it “Canton Fair” to let others know where it is held.
But now, with the city name “Canton” into history. More and more people call it Guangzhou fair instead.