The Caldwell Night Rodeo was organized in 1935 as part of the festivities to commemorate the 25th anniversary of the beginning of irrigation on the Boise project. It was called the Homesteaders’ Silver Jubilee and Night Rodeo. Lights were installed on the grounds and the first night rodeo to be held in southern Idaho was witnessed by thousands of people. Stock was provided by Everett Colborn and Doc Sorenson and $2,500 was put up in prize money. Kid Combs of Caldwell, a professional bronc buster, was the first cowboy to file his name on the entry list for the rodeo.
The rodeo became an annual event in Caldwell and grew bigger and better every year in the l930s thanks to the work and support of the community. It continued into the l940s and only missed two years during the war when President Roosevelt requested that such events not be held.
Tex Ritter, a popular singing cowboy, was the first star of the Caldwell. That was in 1947, and throughout that decade, large crowds and local enthusiasm abounded at the night rodeo.
In l963, the rodeo moved to the brand new Canyon Multi-Purpose Stadium. The crowds felt the tradition had been lost and many did not attend the rodeo the way they had in the past. Hoping to recapture the enthusiasm and support they had enjoyed in the past, the rodeo board made some big changes for the l965 rodeo. A major star, Patti Page, was signed to entertain during the rodeo. The dates were moved up from August to June and the name was changed to Treasure Valley Roundup.
This might have worked in another year but it proved disastrous that year. It rained that week. Shavings were hauled in and strewn over the grassy field at Simplot Stadium. The rodeo grounds crew were told not to water the grass for a week before the rodeo but someone inadvertently watered it just before the shavings were scattered.