Authorized by the California State Legislature in May 1939, the 35-A District Agricultural Association held it's first annual county fair in October 1939. Governor Olson appointed the first Board of Directors: George M. Stark, Jay T. Norman, Daniel Kleiman, Stanley Fiske, James W. Warford, Ray M. Sullivan and E.O. Sumner. George W. Robinson was appointed to act as the first Secretary-Treasurer and was paid $150 for his services from May through December 1939. J.M. Loyd of Auburn was retained as the manager of the first annual county fair. His compensation for managing the fair, performing the auditing work and preparing the 1940 budget was set at $500. Wilbur White was hired as the grounds superintendent for the first annual fair and was compensated $11 per day plus reasonable and necessary expenses.
Planning for the first annual Mariposa County was underway. In two short weeks, the event was planned and organized and opening day arrived.
- The first premium list for exhibits was prepared offering $6,558.25 in cash prizes for Horse Show, Livestock, Poultry/Rabbits, Community Booths, Agriculture, Horticulture, Domestic Science, Bees and Honey, Lumber, Minerals and Future Farmers of America.
- A committee chaired by A. C. McDonald organized an amateur rodeo.
- An entertainment committee was appointed to work out suitable arrangements for the fair's program. Daniel Klieman, Thomas L. Graham, Ruth Womack, J.L. Spriggs, Ramona Eckern, Margaret Black, and C.K. Dennis.
- The "Distinguished Guests Banquet" was organized by J.J. Castegnetto, John L. Dexter and Schottky.
- Electricians engaged in "fair" work were paid 90 cents per hour and the electrician helpers were paid 75 cents per hour.
- The first annual Mariposa County Fair receipts were $3,411.35 and expenses totalled $9,103.00.
A special meeting of the Board of Directors was called to consider renting the fairgrounds for an interim (non fairtime) event.
Over the years, many, many changes have occurred on the fairgrounds and the facility has been continually developed and improved.
- The planning and preparation for today's fair is a year round effort.
- Premiums offered for exhibits at the 1999 fair totaled more than $38,000. for 36 different exhibit categories.
- The Rodeo is CCPRA (California Cowboys Professional Rodeo Association).
- Entertainment for the fair costs over $25,000.00.
- The annual fair of today earns over $200,000. in receipts and the expenses for the event are at least that amount, if not more.
- Hundreds of events are held year around on the fairgrounds.