Here's my n site with modx :)

<div class="dealer New-Jersey Brooklawn" style="display: block;">
<h3>
</h3>
<div class="info">Rt. 130 at Brooklawn Circle, Brooklawn, NJ, 08030 Phone: 856-456-4777   Fax: 856-456-4777</div>
</div>

$provinceCity = array();
$list = "";
$id= $modx->documentObject['id'];
$title= $modx->documentObject['pagetitle'];
$ids = $modx->getActiveChildren($id,'menuindex','','id');
//var_dump($ids);
foreach($ids as $id){
   //echo $id['id'];
    $tvs = $modx->getTemplateVarOutput(array("ProvinceState","RegionCity"),$id['id']);
    
    //clean values using a snippet
    
    $tvs['ProvinceState'] =  $modx->runSnippet("safeName",array("txt" => $tvs['ProvinceState']));
    $tvs['RegionCity'] =  $modx->runSnippet("safeName",array("txt" => $tvs['RegionCity']));
    
    //put values in arrays. Only unique values should exist
    if(!array_key_exists($tvs['ProvinceState'], $provinceCity)){
        $provinceCity[$tvs['ProvinceState']] = array();
        array_push($provinceCity[$tvs['ProvinceState']],$tvs['RegionCity']);
    }else{
        if(!in_array($tvs['RegionCity'], $provinceCity[$tvs['ProvinceState']])){
            array_push($provinceCity[$tvs['ProvinceState']],$tvs['RegionCity']);
        }
    }
}

//make list to be used as select values
foreach($provinceCity as $key=>$val){
    $list .= 'list["' . $key . '"]=\'';
    $list .= '<option value="">Select Region/City</option>';
    foreach($val as $city){
         $list .= '<option value="'.$city.'">'.$city.'</option>';
    }
    
    $list .='\';';//close list
}

echo $list;