The Montgomery County Fair began as Field Days in the 1960s, expanding until it moved to its current fairgrounds in 1968. Officials built the Lone Star Expo Center for the 2001 fair.
The Montgomery County Chamber of Commerce Agricultural Division began the tradition of holding Field Days in the fields of a local ranch or farm, the location of which changed over the years. In the 1960s, Field Days began to resemble the modern Montgomery County Fair. The annual show and auction outgrew their new quarters, the Candy Cane Park Pavilion, in 1965 after just three years. The auction then moved to the Cow Palace auction barn before moving again in 1968 due to the growth of the Junior Livestock Show. The new location was the Montgomery County Fairgrounds.
The Chamber of Commerce began organizing the fair in 1978, and the fair was incorporated in 1979. The Fair Offices arrived at the fairgrounds in 1985 and still reside there as of 2015. The Fair Association added two livestock barns and an exhibit building over the years, and the first major show held in the Lone Star Expo Center was a rodeo. The Montgomery County Fair officials expected approximately 65,000 visitors for the 2015 fair.