var PopulateCities = function (data) {
    $('#CtCity').html("");

    for (var i = 0; i < data.length; i++) {
        var city = data[i];
        $('#CtCity').append('<option value="' + city.id + '">' + city.nome + '</option>');
    }

}

$(function () {

    $('#CtState').change(function () {
        var st = $('#CtState option:selected').val();
        $('#CtCity').html('<option>Aguarde...</option>');
        $.ajax({ url: "Cities.ashx", data: { state: st }, success: PopulateCities, error: function (foo, bar, foobar) { alert(foobar); }, dataType: 'json' });
    }).change();

});