The Liberty Series takes its name from the 3-cent, 8-cent, and 11-cent values picturing the Statue of Liberty. The series started out as a set of seventeen different subjects with eighteen denominations, printed in formats of sheet panes, booklet panes, and coils. Unlike the thirty-two different values of the Presidential Series, many of which saw very little service, the eighteen denominations for the Liberties were selected to ensure no more than two stamps were necessary to pay up to sixty cents in postage, nor more than three for up to $1.60. Over time, eight denominations were added to the original plan (1.25-cent, 2.5-cent, 4.5-cent, 8-cent Pershing, 11-cent, 12-cent, 15-cent, and 25-cent).
The series differed radically from the Presidential series, featuring 'warm portraits' of its subjects as compared to 'hard profile busts' of the earlier series. Famous portrait artists and photographers' works were used as the basis for the designs, such as the work of Rembrandt Peale for the 5-cent James Monroe and the 15-cent John Marshall
The 8-cent red, white, and blue Statue of Liberty stamp, issued on April 9, 1954, was the first of the series. The premiere of this stamp was actually broadcast on national television with President Dwight David Eisenhower presiding! The series was in general use from 1954 through 1973, though some stamps in the series remained on sale through the 1980s.
All stamps were produced by the Bureau of Engraving and Printing, and most were printed by the rotary press. The 8-cent Statue of Liberty was printed on both the flat plate and the Stickney rotary presses. A third version of the 8-cent Liberty as well as the 11-cent Liberty was also printed on the new Giori Press. The 5-dollar Hamilton was printed only on the flat plate press.
As a result of experiments begun at the Bureau in 1953, the series introduced a new 'dry' paper (moisture content 5-10 percent); in previous 'Wet' printings, the paper had a moisture content of 15-35 per cent. The new process required a thicker, stiffer paper, special types of inks and greater pressure to force the paper into the recessed plates producing designs that stood out more clearly. Fourteen denominations were printed on both wet and dry paper.
The phosphor tagging of stamps, applied to facilitate automatic mail handling, was a process pioneered in 1963 and adopted for regular use by 1968. The advent of tagged versions of a stamp unintentionally produced new varieties even though they appear to be identical to the naked eye. The Liberties have many tagged varieties. The first Liberty series stamp to be tagged was the 4-cent Lincoln stamp (1036b), issued November 2, 1963.
Two perforation varieties are found on the Liberty series coil stamps. The coils were initially issued with normal size (large holes) perforation holes and then appeared with small holes, even though they were of the same perforation gauge.
The final stamp in the Liberty Series was issued on February 25, 1965, in Boston, the 25-cent coil featuring Paul Revere, and remained on sale officially until April 30, 1987, a remarkable 22-year run.