Disable specific country at checkout w/ PHP

Hi,

I’d like to remove a specific country from billing and shipping address country drop-downs on a specific checkout page only (client has several, hence PHP).

Right now I have this, which hides the country but leaves an odd space and produces an error.

function wz_remove_canada_checkout_new_orders( $countries ) {
    if ( is_page( 'checkout' ) ); {
        $countries = array(
            'US' => United States
        );
        return $countries;
    }
}
add_filter( 'woocommerce_countries', 'wz_remove_canada_checkout_new_orders' );

Any guidance would be appreciated.