S
- Sabula
- Sac City
- Sageville
- Saint Ansgar
- Saint Anthony
- Saint Benedict
- Saint Charles
- Saint Donatus
- Saint Joseph
- Saint Lucas
- Saint Marys
- Saint Olaf
- Saint Paul
- Saint Sebald
- Salem
- Salina
- Salix
- Sanborn
- Sand Bar Beach Resort and Trailer C
- Sand Springs
- Sandyville
- Santiago
- Saratoga
- Sattre
- Saude
- Savannah
- Sawyer
- Saxon
- Saylorville
- Scarville
- Scenic View Mobile Home Park
- Schaller
- Schleswig
- Schley
- Sciola
- Scotch Grove
- Scotch Ridge
- Scott
- Scranton
- Searsboro
- Sedan
- Seigel
- Selection
- Selma
- Seneca
- Seney
- Sergeant Bluff
- Severs
- Sewa
- Sewal
- Sexton
- Seymour
- Shady Grove
- Shady Oak
- Shaffton
- Shambaugh
- Shannon City
- Sharon
- Sharon
- Sharon Center
- Sharpsburg
- Sheffield
- Shelby
- Sheldahl
- Sheldon
- Shell Rock
- Shellsburg
- Shenandoah
- Sheridan
- Sherman
- Sherrill
- Sherwood
- Shipley
- Shueyville
- Shunem
- Siam
- Sibley
- Sidney
- Sigourney
- Silver City
- Silver Lake
- Sinclair
- Sioux Center
- Sioux City
- Sioux Rapids
- Sixmile
- Sixteen
- Skunk River
- Skyline Mobile Park
- Slater
- Slifer
- Sloan
- Smithland
- Smiths
- Smyrna
- Solberg
- Soldier
- Solomon
- Solon
- Somber
- Somers
- South Amana
- South English
- South Lineville
- Southview Estates Mobile Home Park
- Spaulding
- Spencer
- Spencers Grove
- Sperry
- Spillville
- Spirit Lake
- Spragueville
- Springbrook
- Springdale
- Springdale
- Spring Fountain
- Spring Grove
- Spring Hill
- Springhole
- Spring Valley
- Springville
- Springwater
- Stacyville
- Stanhope
- Stanley
- Stanton
- Stanwood
- Stanzel
- Starlite Mobile Home Park
- State Center
- State Center Junction
- Steamboat Rock
- Stennett
- Sterling
- Steuben
- Stevens
- Stiles
- Stillwell
- Stilson
- Stockport
- Stockton
- Stone City
- Stonega
- Storm Lake
- Story City
- Stout
- Strahan
- Strand
- Stratford
- Strawberry Point
- Streepy
- Stringtown
- Struble
- Stuart
- Sully
- Sulphur Springs
- Summerset
- Summit
- Summit
- Summitville
- Sumner
- Sunbury
- Sundusky
- Sunfield Mobile Home Park
- Sunrise Mobile Court
- Sunrise Mobile Home
- Sunshine
- Superior
- Sutherland
- Sutliff
- Swaledale
- Swan
- Swanton
- Swea City
- Swedesburg
- Sweetland Center
- Swisher