When fully assembled, each of the boosters stood nearly fifteen stories high and weighed 590 tons—the largest solid rockets ever built; before each shuttle flight, a pair of them had to be transported on eight heavy-duty flatbed railcars across the country, from the manufacturing facilities of the contractor, the Thiokol Corporation, in northwestern Utah, to Cape Canaveral: a twelve-day journey crossing eight states, covering more than two thousand miles.
