The 1854 Gazetteer of the United States by Thomas Baldwin shows:

CASS, a county in the W. central part of Illinois, has an area of about 350 square miles. It is bounded on the N. W. by the Illinois, and on the N. by the Sangamon river. These streams unite on the border of the county. The surface is nearly level, consisting partly of prairie and partly of timbered land: the soil is excellent. Indian corn, wheat, oats, hay, and pork are the staples. In 1850 it produced 1,417,750 bushels of corn, 131,136 of wheat; 150,197 of oats, and 3385 tons of hay. It contained 14 churches and 1 newspaper office. There were 1000 pupils attending public schools. The rivers above named are navigable by steamboats on the borders of the county. Capital, Beardstown. Population, 7253.