The first fair on the grounds of the now Twin Falls County Fair was September 20 - 23, 1916 and was called the Southern Idaho Fair.
"The following description of the Fair entries and parade from the FILER JOURNAL, September 21, 1916: "Under the clearest skies opened the first annual meeting of the Southern Idaho Fair Wednesday morning. With everything working like clockwork, the gates were thrown open and from an early hour it could be predicted that the Twin Falls County Fair was going to be the success as the little handful of Filer Boosters had predicted. Everyone connected with the Fair was on his toes to see that no mistake had been made when the County Commissioners had lent their aid to make the Fair at Filer, a creditable and successful one. All the many horse and stock stalls were taken the morning of the first day which insured the success of this essential part of the fair. The exhibits for the different buildings also rapidly filled."
The name of the fair was changed to the Twin Falls County Fair in 2018.