ido-save-directory-list-file

ido-save-directory-list-file is a variable defined in `ido.el'.
Its value is

"~/.emacs.d/ido.last"

Documentation:
File in which the Ido state is saved between invocations.
Variables stored are: `ido-last-directory-list', `ido-work-directory-list',
`ido-work-file-list', and `ido-dir-file-cache'.
Must be set before enabling Ido mode.

You can customize this variable.

This variable was introduced, or its default value was changed, in version 24.4 of Emacs.