By helping larger ships with docking and sailing, the tiny but powerful tugboat helps keep traffic flowing smoothly and safely in the world's seaports. Before the Revolutionary War, rowboats manned by eight to ten men were used as tugs.
The Transportation Series
A ground-breaking stamp was quietly issued on May 18, 1981. For the first time in U.S. history, a coil stamp featured its own unique design rather than simply copying that of the current definitive stamp. Fifty more coil stamps would be issued over the course of the next 15 years, each picturing a different mode of transportation.
The various denominations provided face values to exactly match the rates for several categories of Third Class mail (bulk rate and quantity-discounted mail). As the rates changed, new stamps with new values were added. Never before had a stamp series included so many fractional cent values.
Most of the stamps in the Transportation Series were printed by the Bureau of Engraving and Printing, although a few were printed by private contractors. All but a few of the later stamps were produced by engraved intaglio.
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