$(document).ready(function () {

    var $country = $('tr.row-data-country select[name*=country]');
    var $stateRow = $('tr.row-data-state');
    var changeCountry = function () {
        if ($country.val() == 'US')
            $stateRow.show();
        else
            $stateRow.hide();
    };
    changeCountry();
    $country.change(changeCountry);

});