<select class="multi-select">
  <optgroup label="Alaskan/Hawaiian Time Zone">
    <option value="AK">Alaska</option>
    <option value="HI">Hawaii</option>
  </optgroup>
  <optgroup label="Central Time Zone">
    <option value="AL">Alabama</option>
    <option value="AR">Arkansas</option>
    <option value="IL">Illinois</option>
    <option value="IA">Iowa</option>
  </optgroup>
  <optgroup label="Eastern Time Zone">
    <option value="CT">Connecticut</option>
    <option value="DE">Delaware</option>
    <option value="FL">Florida</option>
  </optgroup>
</select>