This gist if for people who use WooCommerce and wants the hook to add a dropdown with french states at the checkout.

WooCommerce - French States

<?php

/**
 * Add or modify States for France
 * Description : Active the dropdown with all the french states without overseas departments. Copy/Paste in your functions.php in your child-theme. You need to have the plugin WooCommerce
 * Version: 1.0
 * Author: Guillaume Forgue
 * Author URI: http://guillaume-forgue.fr
 */

/**
 * Copyright (c) 2012 Guillaume Forgue. All rights reserved.
 *
 * Released under the GPL license
 * http://www.opensource.org/licenses/gpl-license.php
 *
 * This is an add-on for WordPress
 * http://wordpress.org/
 *
 * **********************************************************************
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
 * GNU General Public License for more details.
 * **********************************************************************
 */
 
add_filter( 'woocommerce_states', 'custom_woocommerce_states' );

function custom_woocommerce_states( $states ) {

  $states['FR'] = array(
    'GE' => 'Grand Est', 
    'NA' => 'Nouvelle-Aquitaine',
    'ARA' => 'Auvergne-Rhône-Alpes',
    'BFC' => 'Bourgogne-Franche-Comté',
    'BR' => 'Bretagne',
    'CVDL' => 'Centre-Val de Loire',
    'IDF' => 'Île-de-France',
    'OC' => 'Occitanie',
    'HDF' => 'Hauts-de-France',
    'NO' => 'Normandie',
    'PDLL' => 'Pays de la Loire',
    'PACA' => 'Provence-Alpes-Côte d\'Azur',
    'CR' => 'Corse',
  );

  return $states;
}