Total population (1990 census): 35687
County seat: Ottumwa
Crop Statistics (1997 US Census of Agriculture)
| Cereals | Farms | Acres | Yield | |
| Maize=Corn | 331 | 48851 | 6408454 bu | |
| Wheat for Grain, Total | 11 | 199 | 8940 bu | |
| Oats | 48 | 1113 | 91043 bu | |
| Grain Legumes | Farms | Acres | Yield | |
| Soybean | 320 | 51014 | 2332218 bu | |
| Forages | Farms | Acres | Yield | |
| Total Hay* | 420 | 18609 | 44351 tons, dry | |
| Alfalfa Hay | 309 | 11268 | 31016 tons, dry | |
| Small Grain Hay | 28 | 498 | 1035 tons, dry | |
| Tame Hay | 152 | 5538 | 10208 tons, dry | |
| Wild Hay | 22 | 787 | 967 tons dry | |
| Grass Silage | 13 | 518 | 3374 tons, grn | |
| Corn for Silage | 21 | 555 | 9618 tons, grn | |
| Vegetables | Farms | Acres | Yield | |
| Sweet Corn | 3 | D | ||
| Fruits | Farms | Acres | Yield | |
| Apples | 6 | D | 2507 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 | 12 | D | 29 | 263 |
| Florculture Crops | 5 | D | D | D |
| Bedding/Garden Plants | 5 | D | D | D |
| Cut Christmas Trees Harvested | 5 | X | 11 | 18 |
| Other Nursery and Greenhouse Crops | 3 | D | 13 | 3 |
*Alfalfa, grass silage, green chops etc.
D=Withheld to avoid disclosing data for individual farms.
X=Not applicable.