Chili, tacos, refried beans — we picture beans in warm Southwestern kitchens. But the fields that grow them are somewhere much colder.
Kidney, pinto, navy and black beans are all seeds of the common bean plant, left to dry and then stored. That's why they're called dry beans.
Basis: Botany: dry edible beans are mature, dried seeds of Phaseolus vulgaris — textbook.
Even though we link beans to warm Southwestern and Mexican food, the biggest U.S. dry-bean harvests come from cool northern states — the northern Plains and Great Lakes, not the desert Southwest.
Basis: USDA NASS dry-bean production by state (this site's dry-beans quiz).
Beans are legumes: tiny bacteria living on their roots can pull nitrogen — a natural plant food — straight out of the air, which is why legumes have a reputation for being kind to the soil.
Basis: Plant science: legume–rhizobia nitrogen fixation — established.
Do dry beans really refresh a field for the next crop? Farmers do rotate beans with hungrier crops like wheat, but a dry-bean harvest actually leaves less nitrogen behind than some other legumes — so treat 'beans feed the soil' as only partly true.
Why the north? A common explanation is that cool summers and a dry harvest season let the beans dry down cleanly in the field without rotting. Plausible, but the exact reason a crop belt lands where it does is hard to pin to one cause.
※ A hypothesis is an idea that isn't proven yet.
📊 Sources for the rankings mentioned in this note (links to the original data and retrieval dates) are on each quiz page below.