Total population (1990 census): 14630
County seat: Marengo
Crop Statistics (1997 US Census of Agriculture)
| Cereals | Farms | Acres | Yield | |
| Maize=Corn | 614 | 112493 | 14753816 bu | |
| Wheat for Grain, Total | 7 | 427 | 22465 bu | |
| Oats | 167 | 3601 | 261835 bu | |
| Rye | 5 | 45 | 1421 bu | |
| Grain Legumes | Farms | Acres | Yield | |
| Soybean | 573 | 76935 | 3789169 bu | |
| Forages | Farms | Acres | Yield | |
| Total Hay* | 453 | 20944 | 64559 tons, dry | |
| Alfalfa Hay | 403 | 17047 | 56207 tons, dry | |
| Small Grain Hay | 44 | 859 | 1521 tons, dry | |
| Tame Hay | 68 | 1838 | 3255 tons, dry | |
| Wild Hay | 10 | 285 | 475 tons dry | |
| Grass Silage | 20 | 915 | 9300 tons, grn | |
| Corn for Silage | 92 | 2739 | 44028 tons, grn | |
| Sorghum for Silage | 7 | 118 | 1300 tons, grn | |
| Vegetables | Farms | Acres | Yield | |
| Pumpkins | 10 | 28 | ||
| Sweet Corn | 6 | 55 | ||
| Watermelons | 3 | D | ||
| Fruits | Farms | Acres | Yield | |
| Apples | 5 | 8 | D | |
| Nursery and Greenhouse Crops, Cut Christmas Trees Harvested, Mushrooms, and Sod Grown for Sale | Farms | Sq. ft. under glass or other protection | Acres in the open | Sales ($1,000) |
| Nursery and Greenhouse Crops | 3 | D | D | D |
| Cut Christmas Trees Harvested | 3 | X | 10 | D |
*Alfalfa, grass silage, green chops etc.
D=Withheld to avoid disclosing data for individual farms.
X=Not applicable.