Arthur G Peterson wrote a series of comprehensive books on salt shakers in the 1960's.  The last book which contained all of the material from previous editions, "Glass Salt Shakers: 1,000 Patterns", was published in 1970.  Dr Peterson was a thorough researcher fascinated by patent dates associated with shaker designs and functions as well as flowers used for the decor of some.  He named many of the shakers which to that date had not been identified.  Many Victorian glassware patterns,  later researched by Bill Heacock and other authors, got their names from the name given to the salt shaker by Dr Peterson. 

He was particularly fascinated by the clear shaker, now known as "The Pioneer", because it had a patent date of "September 15, 1863" on the bottom of the shaker.  He then speculated that perhaps this shaker was the the first shaker that had a screw on cover.  Earlier shakers required a metal sleeve to be fastened to the glass with plaster of paris so that a screw on cover could then be attached to the metal sleeve.  This being required since the technology to consistently make glass threads of the same size on the shaker.  He felt that if his speculation was indeed fact, then this shaker deserved a special place in history.

Further research by Dr Peterson was published in 1973 in his book, "Glass Patents and Patterns".  The first patent relating to a salt shaker was issued September 15, 1863 to C.P. Crossman.  It was for a stationary agitator to break up the salt which always formed lumps and also clogged up the holes in the top.  No other patent was issued at that date.  His conclusion was that the date on the Pioneer shaker was in reference to the Crossman patent date for the agitator.  It was customary at that time to put the patent date on the article even the patent was for the agitator inside. 

Although the significance of The Pioneer shaker was not as originally speculated by Dr Peterson, it still holds a special significance as one of the first shakers which bore the patent date of the first patent issued specifically for a salt shaker.

Another shaker, the Pioneer Companion, also has that date imprinted in the glass of the shaker.