Prior to the late 19th century, pipe organ wind pressures ranged mostly in the area of 2" to 4" of water column. Organs were pumped by hand and foot power, and tracker action was the norm. Together, these two elements limited the pressures which could be generated. Attempting to play a straight tracker organ at wind pressures higher than 4" would be hard on the fingers. and coupling multiple manuals at such pressures would require great playing effort.
With the introduction of steam, water power, gas engines, and electricity, wind pressures increased, since there was unlimited power to operate the blower, and fingers became detached from operating the valves in the windchests. Playing an electric action organ on 2" wind pressure was no more difficult than playing one on 25".
Beginning in the late 1800s, wind pressures gradually rose until they reached a peak of 100" in the Atlantic City organ in 1931. Such extreme pressures are rare, and most organs in the period 1910-50 would have wind pressures in a range of from 4" to 10", with some big reeds up to 25". With the revival of tracker action in the 1950s and '60s, wind pressures dropped to lower levels, and many instruments operated in the unhistoric range below 2". I don't know what the lowest wind pressure was in the 1960s, but it might have been about 1". Such experiments were short-lived, and by the 1980s, most pipe organs were being built and voiced with pressures ranging from 3" to 4". These years from 1950 to 1980 marked the period of Baroque revival with tonal designs reflecting a modern interpretation of organ styles before 1750, and, in many cases, an anti-Romantic stance. The results of this movement were interesting and informative but many neo-Baroque instruments missed the mark of reviving the actual style and sound of the earlier designs, and produced an entirely new type of instrument with a character and sound all its own. The Baroque revival did not produce any actual Baroque instruments, but the results were important, far-reaching, and remain with us today. The implementation of early tonal schemes, voicing, performance, and organ architecture has been widespread and of inestimable importance in current organbuilding.
In the 1980s, wind pressures began rising again. Just as in the late 19th century, organ design has begun to move into Romantic areas as neo-Baroque (not Baroque) ideas fade. Large tracker organs are being built with equipment to assist playing on higher wind pressures, and electric-action instruments are reaching into pressures above 7", not common for more than 40 years. The demise of the large pipe organ which was predicted some years ago has not come to pass, and large instruments with powerful voicing, high wind pressures, and eclectic design have returned to the scene with a sound and excitement which is unexpected. Cavaillé Coll is the talk of the day, and builders are scrambling to understand everything about the French Romantic organ while creating their own interpretations of it. The American Classic organ (1930-1960) is having a similar revival, claiming a new validity after the interruption in its development during the neo-Baroque era.
It is uncertain where the current trend in wind pressure is going. If a graph of pressures were made, it would be quite level from ancient times to about 1870 when it began to rise toward a peak in the 1930s. A steep decline in the graph took place in the 1950s and 60s, and a rise is now under way again, repeating the effects seen in the earlier part of this century.
Perhaps we will see a broad and highly individual use of wind pressures. Some builders will stay in the area of 21/2" - 4", while others will utilize pressures above that, depending on the sonic power needed for the situation or the tone color desired (a pipe organ French Horn needs at least 10" wind pressure to be successful). This is in character with the ever-broadening styles available in contemporary organbuilding, and an indication of the life and continued development of the pipe organ in our world of music.