Home Postcode finder SA American River American River postcode SA American River is a locality in South Australia covered by postcode 5221. Postcode 5221 State or territory South Australia (SA) Region Sa Subs Near 2 Add a free American River business listing Be the first listing in American River Common questionsWhat is the postcode for American River?American River, SA has the postcode 5221.What state is American River in?American River is in South Australia (SA).Does postcode 5221 cover more than one suburb?Yes. Postcode 5221 covers 3 localities, so the postcode alone does not identify American River. Browse other postcodes in South Australia, or widen the search to every Australian postcode.