$(document).ready(function () {
  $('select#search_form_region').append('<option value="other">Other Region...</option>');

  $('select#search_form_region').change(function () {
    if ($('select#search_form_region').val() == 'other') {
      $('div#other-region').show();
    } else {
      $('input#search_form_other_region').val('');
      $('div#other-region').hide();
    }
  });

  if ($('input#search_form_other_region').val()) {
    $('select#search_form_region').val('other');
    $('div#other-region').show();
  }
});