Between 1865 and 1900, rural Kansas changed dramatically as settlers spread across the state, and veterans of the Union Army and European emigrants founded towns such as Belleville. In Republic County, a county agricultural society was organized in 1871, and the first county fair was held that fall, but both ended in 1878 when drought and recession led county commissioners to withdraw financial support. Along Kansas's northern border, corn was the dominant crop, but by 1890 winter wheat had become more profitable, and diversified farming was established in Republic County. Farmers raised corn and wheat, cattle and hogs, horses and mules, and also produced alfalfa, sorghum, milk, butter, eggs, and produce. From 1879 to 1904, Republic County hosted a Corn Carnival, and towns like Belleville became local markets for crops and livestock, while tradesmen and manufacturers supplied implements, repairs, and services to farmers. County offices and court sessions in the Republic County Courthouse also brought farmers to Belleville for business and legal matters. The Golden Age of Agriculture from 1900 to 1914 supported local investment in Belleville's infrastructure, buildings, and institutions. Republic County's population reached 18,248 in 1900. Reorganized in 1905, the county fair in Belleville began receiving a county tax levy after 1919, and by 1930 the North Central Kansas Free Fair had become the third largest agricultural fair and livestock show in Kansas. Beginning in 1910, auto racing entertained fairgoers, and in the 1930s a high-banked clay oval was built; auto racing remains an important attraction in Belleville. By 1964, local historian Louise Carstensen remarked that in less than a hundred years a miracle had come about in the farm houses and on the homesteads of Republic County. As railroads declined, local businesses depended even more on farmers' trade, a pattern reflected in the success of downtown Belleville throughout the community's history.