The Fairplex has been the home of the L.A. County Fair since 1922. Known prior to 1984 as the Los Angeles County Fairgrounds, it is located in the city of Pomona, California. The L.A. County Fair is held during the month of May since 2022, but the facility is used year-round to host a variety of educational, commercial, and entertainment such as trade …The Fairplex has been the home of the L.A. County Fair since 1922. Known prior to 1984 as the Los Angeles County Fairgrounds, it is located in the city of Pomona, California. The L.A. County Fair is held during the month of May since 2022, but the facility is used year-round to host a variety of educational, commercial, and entertainment such as trade and consumer shows, conventions, and sporting events.