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

LEE, a county in the N. part of Illinois, has an area of 700 square miles. It is intersected by Rock river, and also drained by Green river and Bureau creek. The surface is nearly level, and the soil excellent. The county is principally prairie, but portions of it are covered with timber. Indian corn, wheat, and oats are the staples. In 1850 this county produced 232,010 bushels of corn; 97,538 of wheat; 99,562 of oats, and 8661 tons of hay. It contained 6 churches, 1518 pupils attending public schools, and 40 attending other schools. It is intersected by the Galena Branch of the Central railroad. Named in honor of General Lee of the Revolutionary war. Capital, Dixon. Pop., 6121.