How do you find room for 150,000 one page letters in one canvas mail bag?
You microfilm it! This is what the U.S. Post Office Department did during World War II. It was a space saver to the tune of 36 mail bags or 2,530 pounds. From June 15, 1942 to April 1, 1945, this space was used for essential cargo needed for the troops overseas. There were a total of 556.5 million letters going to service persons and 510 million sent home from the front.