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/**
 * Code goes in functions.php or a custom plugin. Replace XX with the country code your changing.
 */
add_filter( 'woocommerce_states', 'custom_woocommerce_states' );

function custom_woocommerce_states( $states ) {

  $states['XX'] = array(
    'XX1' => 'State 1', 
    'XX2' => 'State 2'
  );

  return $states;
}