The exact location of Whoville seems to vary depending on which book or media is being referenced. According to the book Horton Hears a Who!, the city of Whoville is located within a floating speck of dust which is then placed onto a clover flower by Horton the Elephant. In the book How the Grinch Stole Christmas!, Whoville is located south of Mt. Crumpit, but its overall location is never directly mentioned. Further, in the 1977 television special Halloween Is Grinch Night, additional geographic features are added to Whoville such as Punkers Pond. Again, however, its greater location is not mentioned, but in both works it can be assumed Whoville is still located within its speck on the clover.
In the 1970 television special Horton Hears a Who! as well as the 2008 CGI-animated film of the same name, Whoville retains its literary location being within a speck on a clover flower. The 1966 television special How the Grinch Stole Christmas! also stays true to the literature.
In the 2000 live-action film adaptation How the Grinch Stole Christmas, from Universal Pictures and Imagine Entertainment, Whoville is located south of Mt. Crumpit within the mountainous Highrange of Pontoos, described in the movie’s introduction. All of which is located inside the frozen crystal structure of a snowflake, rather than on a clover flower.
Because the city of Whoville resides on a speck, it is possible Whoville is prone to unexpected movement, weather, and activity, and may from time to time change location altogether. In fact, this unexpected movement was used as a major plot device in the 2008 film.