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

EDGAR, a county in the E. part of Illinois, bordering on Indiana, a few miles from the Wabash river: area about 600 square miles. It is drained by Brulette and Clear creeks, affluents of the Wabash river, and by Little Embarras river. The surface presents no great inequalities; the soil is good. The county contains extensive prairies, and many parts of it are well timbered. Indian corn, wheat, oats, pork, wool, and butter are the staples. In 1850 it produced 1,250,278 bushels of Indian corn; 49,424 of wheat; 138,830 of oats, and 174,828 pounds of butter. It contained 19 churches, 1 newspaper office, 690 pupils attending public schools, and 165 attending academies or other schools. Named in honor of Colonel John Edgar, one of the earliest and most distinguished pioneers of Illinois. Capital, Paris. Population, 10,692.