The Adams County Fair is almost as old as the county itself.

The first official Adams County Fair was held in October 1904, but the fair and rodeo predate the formation of the county. The fair dates back to 1888, when monthly Market Days were held at the fairgrounds on the south edge of Brighton, which is the present-day site of the City of Brighton Government Center at 450 South 4th Avenue.

The monthly Market Day for farm produce and livestock was organized by Brighton founder Daniel F. Carmichael and other Brighton boosters. The site was a racetrack called Driving Park, where horse races and plowing races took place and cattle and horses were auctioned. The fairgrounds also was the site of July 4th celebrations for several years.

The Platte Valley Farmers Association launched a fall fair in Brighton in 1892. The scope of this project was larger than ever before and embraced several counties. Buildings were erected at Driving Park to house exhibits. A 120' x 32' grandstand that could seat 500 people was built next to the racetrack with a fine arts hall underneath. A tent eight feet in diameter was constructed to shelter displays of agricultural products. Stalls for horses, sheds for cattle, and pens for hogs were built on the south of the racetrack.

A long list of premiums and awards were donated by local businessmen, including the Fulton Ditch Company, Arapahoe County, and various Denver business firms. On October 5, 1892, the day the fair was to begin, Brighton was hit by a terrible rain storm and the fair was postponed. Fortunately, the storm struck before the exhibits arrived, and the only real damage at the fairgrounds was to the tent, which was flattened by the high winds. The fair was finally held October 18-20.

Tomato Day - Battle of Brighton

After the voters of Adams County chose Brighton as the permanent county seat, the fairgrounds were turned over to the newly formed Adams County Fair and Rodeo Association. The first Adams County Fair and Rodeo was held during the first week of October 1904. Opening day was known as Tomato Day and was the day with the best attendance. A noon barbecue was followed by a tomato contest called the Battle of Brighton. Two teams of eight contestants dressed in white represented the Democratic and Republican opponents for county offices. The two teams lined up and faced each other in front of the grandstand. Each team member was given a box of ripe tomatoes, and on command they disposed of the fruit as quickly as possible by throwing it at the opposing team and occasionally the spectators. Read all about the tomato fights from a newspaper article dated October 2, 1904.

The next year the popular event was held between teams from Brighton and Fort Lupton. Other events were wild-bronco riding, half-mile foot races, bicycle and motorcycle races, a mule race, horse races of various sorts, and a baby contest. Over the years famous or soon-to-be-famous performers participated in the rodeo, including African American cowboy Nat "Dead Wood" Dick Love, who once worked as a horse trainer at the Driving Park in Brighton.

The Adams County Fair continued to grow until the old fairgrounds became too small.

In 1964, the Adams County Board of County Commissioners decided to move the fair to the former site of the Denver Poor Farm near Henderson, where new facilities were constructed. The 4-H building was the only structure saved and moved to the new Adams County Regional Park.