If they died, the silk filaments of their cocoons would be ruined. From Seattle draw an arrow eastward through Minneapolis, Chicago, and ending in Boston. Trains carrying silkworm cocoons in specially heated cars left the ports of Seattle and Tacoma, Washington, and dashed across the United States. After arriving at the textile mills in New England, the cocoons were steamed, killing the silkworm inside. Each cocoon is made up of a single silk filament 2-3,000 feet long.
Several cocoons are then unraveled and twisted together to make the thread for weaving.
As in the days of the ancient Silk Road, many special routes are in use today. Some carry logs and lumber. Others may carry iron ore, coal, or grain. Still others may carry gasoline, cars, the mail, or even fresh food items. Although most of these routes follow traditional roads and sea lanes, many trace invisible trails through the air.