The Sioux City Area Office also manages the Sheldon Branch Office. If you have any questions or concerns, please contact the Area Office Supervisor, Brittney Gutzmann. Address 2508 East 4th St. Sioux City, IA 51101 United States Phone Number (712) 255-8871 Fax Number (712) 560-3785 Counties Served Ida Lyon Monona O' Brien Osceola Plymouth Sioux Woodbury Email Office