In Britain these chemicals and drugs firms are still located next to salt: some atop the slab of halite in Cheshire, others in Teesside where we used to extract salt. It is not for nothing that American chemicals giant Dow is headquartered in Michigan, above those deep rock-salt formations that sit beneath Detroit. As the trucks come and go with chemicals and pharmaceuticals, they are essentially retracing the same ancient salt routes as our ancestors.
