Q: Where in Kansas does the Wizard of Oz start?
Although, it's rumored that Dorothy Gale is from Liberal, Kansas, there is no written proof of where she is from. In the original story by Frank L. Baum, no specific location in Kansas is given. See Wizard of Oz (available via Project Gutenberg)
That said, Liberal, Kansas is the current home of Dorothy's house.
For more information: Seward County Museum - Dorothy's House