Change the default state and country on the checkout in WooCommerce

/** 
 * Manipulate default state and countries
 * 
 * As always, code goes in your theme functions.php file
 *
 * @see http://docs.woothemes.com/document/change-the-default-state-and-country-on-the-checkout/
 */
add_filter( 'default_checkout_country', 'change_default_checkout_country' );
add_filter( 'default_checkout_state', 'change_default_checkout_state' );
 
function change_default_checkout_country() {
  return 'XX'; // country code
}
 
function change_default_checkout_state() {
  return 'XX'; // state code
}