Earth is the main planet of the show, where Bootsville is located.
In The Kat Went Back Part 2 when Dr. K programs a ship to take everyone home, a diagram of green lines on blue is shown of the Americas in the western hemisphere.
Illegible red text with a red line pointing to a red circle on the west coast of North America may be where Bootsville is located. It appears to be in or near Vancouver. It is unclear whether it is Canada or United States, as neither nation is explicitly referenced in the show, although England has.