This greatest power dam, largest power house and electrical installation, and by far the greatest water-power development in the world, is in the Mississippi River at Keokuk, Iowa. The whole work is a monolith of concrete with a total linear measurement of two miles and a half. The dam proper is nearly a mile long; the power house a third of mile long; the lock is the same width as those at Panama and with one-fourth higher lift than any on the Isthmus; the dry dock is the largest in fresh water. Over 300,000 horse-power is developed, 200,000 of which is available for manufacturing. Fort Madison, Twenty-five miles distant, expects to benefit greatly by the industrial growth this water-power will stimulate.