United States Government--postal Service 102 W 2nd Ave Flandreau, SD 57028 Phone : (605) 997-3202 Business Category Government Offices-Federal Government Offices & Public Schools Post Office - Flandreau 102 W 2nd Ave Flandreau, SD 57028 Phone : (605) 997-3202 Post Office - Flandreau Business Category Post Offices Toll-Free           (800) ASK-USPS Fax           (605) 357-4906