In 1863, the first City Free Delivery Service letter carriers used leather satchels to carry the mail along their appointed rounds. During the first quarter of service, New York City carriers delivered 2,069,418 letters.
For many years, letter carriers were required to lug as much as 70 pounds of mail matter in their leather mailbags. And, before the advent of Parcel Post in 1913, carriers were compelled to load their satchels with all sorts and sizes of packages. Now, generally no packages weighing over two pounds are delivered by the carrier on foot.
As businesses and populations flourished over the next century, carriers' mail loads swelled to enormous burdens. But, as the volume even and the nature of mail changed—one thing remained constant—the leather mailbag.
The Post Office Department tried to change that in 1973, when they decided to replace the leather satchels with canvas ones. Yet, even though the traditional leather satchels are twice as heavy (3-4 pounds) as canvas bags, carriers were reluctant to make the switch. Leather certainly held up well to the demands of the mail delivery, many of the satchels survived six or more years of service. Most carriers, in fact, sought out old, yet functioning replacement leather mailbags rather than use the new canvas satchels.
The canvas bags, which were not as sturdy, wore out in less than two years, and certainly were no match for leather bags when it came to fending off dogs along the route. But, even the sturdiest leather bags wore out after time, and with only canvas bags available as replacements, carriers had no choice but to switch. By the late 1980s, almost all carriers were using canvas bags.