Total population (1990 census): 38276
County seat: Marshalltown
Crop Statistics (1997 US Census of Agriculture)
| Cereals | Farms | Acres | Yield | |
| Maize=Corn | 614 | 130504 | 17459458 bu | |
| Wheat for Grain, Total | 5 | 46 | 1855 bu | |
| Oats | 52 | 963 | 69749 bu | |
| Rye | 3 | 7 | 135 bu | |
| Grain Legumes | Farms | Acres | Yield | |
| Soybean | 616 | 120612 | 5965650 bu | |
| Forages | Farms | Acres | Yield | |
| Total Hay* | 299 | 8873 | 27084 tons, dry | |
| Alfalfa Hay | 266 | 6613 | 22321 tons, dry | |
| Small Grain Hay | 38 | 582 | 1050 tons, dry | |
| Tame Hay | 52 | 1168 | 2752 tons, dry | |
| Wild Hay | 11 | 166 | 354 tons dry | |
| Grass Silage | 6 | 344 | 1822 tons, grn | |
| Corn for Silage | 43 | 1371 | 25643 tons, grn | |
| Vegetables | Farms | Acres | Yield | |
| Pumpkins | 5 | 21 | ||
| Sweet Corn | 3 | 14 | ||
| Tomatoes | 3 | 1 | ||
| Fruits | Farms | Acres | Yield | |
| Apples | 6 | D | 2300 trees | |
| 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 | 13 | 179248 | 67 | D |
| Florculture Crops | 4 | 179248 | D | D |
| Bedding/Garden Plants | 4 | 179248 | D | D |
| Cut Christmas Trees Harvested | 8 | X | 28 | 105 |
*Alfalfa, grass silage, green chops etc.
D=Withheld to avoid disclosing data for individual farms.
X=Not applicable.