The following municipalities have been added to the 2012 Municipal Code Book Index in no particular order during the 1st Major Update period on September 18, 2012:
- Village of Sparland
- Village of Malta
- Village of Lomax
- City of Riverton
- Village of Lemont
- City of Highland Park
- Village of Hoffman Estates
- Village of Midlothian
- City of Ullin
- City of Kenney
- Village of Andover
- Village of Somonauk City
- City of Franklin Grove
- City of Harvard
- Village of Gardner
- Village of Hodgkins
- Village of La Grange Park
- Village of Sleepy Hollow
- Village of Union
- Village of Moweaqu
- Town of Waynesville
- City of Joliet
- Village of Capron
- Village of Rutland
- Village of Illiopolis
- City of Auburn
- City of Bluffs Village
- City of Cave In Rock
- Village of Fox River Grove
- City of Rosiclare
- City of Crescent
- Village of Thomasboro
- Town of Woodhull
- Village of Winnebago
- City of McHenry
- Village of Carlock
- City of Lincoln
- Town of Kickapoo
- Village of Maquon
- Village of Bethany
- Village of De Witt
- Village of Taylor Springs
- Town of Princeville
- Village of Rock City
- Village of Richton Park
- Village of Aviston
- Village of Patoka
- Village of Lovington
- Village of West Brooklyn
- City of Shannon
- City of Pana
- Village of Ipava
- Village of Stockton
- City of West Salem
- Village of Deer Creek
- City of Seatonville
- Village of Melvin
- City of Versailles
- City of East Galesburg
- Village of Justice
- Village of Italian
- Town of Ellsworth
- Village of Stonington
- Town of Blandinsville
- Village of Shorewood
- City of Albers
- Village of Palestine
- Village of Cissna Park
- City of Duquoin City
- Village of Creston
- Village of Pearl City
- City of Cisne
- Village of Odin
- City of Hindsboro
- City of Berwyn
- Town of Shipman
- City of Wood Dale
- Village of Neponset
- City of Arcola
- Village of Owaneco
- City of Taylorville
- City of Table Grove
- City of Gilman
- Village of Lenzburg
- City of Fulton
- Village of Murrayville
- City of Catlin
- City of Collinsville
- City of Utica
- Town of Augusta
- City of Martinsville
- Village of South Pekin
- Village of Oquawka
- City of Cutler
- Village of Ford Heights
- City of Warrenville
- Town of Rockbridge
- Village of Round Lake
