Drop down progression - long version

HTML

<script src="http://documentcloud.github.com/underscore/underscore.js"></script>
<div id="mod">
    <select id="zone">
        <option value="0">-- Select Zone --</option>
    </select>
    <select id="region" disabled>
        <option value="0">-- Select Region --</option>
    </select>
    <select id="state" disabled>
        <option value="0">-- Select State --</option>
    </select>
    <select id="county" disabled>
        <option value="0">-- Select County --</option>
    </select>
    <select id="code" disabled>
        <option value="0">-- Select Code --</option>
    </select>
</div>

CSS

#mod select {
    display:block;
    width:160px;
    margin-bottom:5px
}

JavaScript

var data = {
    "zone01": [{
        "region": "North",
            "state": "New York",
            "county": "Albany",
            "code": "01"
    }, {
        "region": "North",
            "state": "New York",
            "county": "Albany",
            "code": "05"
    }, {
        "region": "North",
            "state": "Maine",
            "county": "Auburn",
            "code": "07"
    }],
        "zone02": [{
        "region": "South",
            "state": "Florida",
            "county": "Gainseville",
            "code": "82"
    }, {
        "region": "South",
            "state": "Florida",
            "county": "Macclenny",
            "code": "73"
    }, {
        "region": "South",
            "state": "Mississippi",
            "county": "Adams County",
            "code": "104"
    }, {
        "region": "Southwest",
            "state": "Texas",
            "county": "Anderson",
            "code": "88"
    }]
};

$.each(data, function (k, v) {
    var zone = JSON.stringify(k);
    zone = zone.replace(/"/g, '');
    $('#zone').append('<option value="' + zone + '">' + zone + '</option>');
});

$('#mod select').change(function () {
    var pick = $(this).attr('id');
    var zoneValue = $('select#zone option:selected').val();
    var regionValue = $('select#region option:selected').val();
    var stateValue = $('select#state option:selected').val();
    var countyValue = $('select#county option:selected').val();
    var codeValue = $('select#code option:selected').val();
    switch (pick) {
        case 'zone':
            $('select#region').removeAttr('disabled').val('0');
            $('select#region option:not([value="0"])').remove();
            $('select#state option:not([value="0"])').remove();
            setValues('zone', zoneValue);
            $('select#state').attr('disabled', 'disabled').val('0');
            $('select#county').attr('disabled', 'disabled').val('0');
            $('select#code').attr('disabled',...