gistfile1.txt

// Hidden form on checkout page

<div style="display: none">
    {exp:cartthrob:save_customer_info_form 
        return=""
    	id="customer_form"
    }
        <input type="hidden" name="country_code" id="hidden_country" value="" />
    {/exp:cartthrob:save_customer_info_form}
</div>

// /checkout/shipping template

{exp:cartthrob:cart_shipping}