Even as the U.S.-flag fleet shrank nearly by half, the number of vessels able to carry more than 15,000 tons of cargo rose from 49 in 1968 to 119 in 1974. New steam-turbine engines helped boost the average speed of large U.S.-flag freighters from just 17 knots in 1968 to 21 knots in 1974. The difference was enough to cut a full day off a transatlantic crossing.
