Spruce Gum is made from the sap of spruce trees. In North America, it is known that spruce gum was chewed by the Native Americans. Spruce gum was later introduced to the early american pioneers and was sold commercially by the 19th century.
Sprucegum continued to be sold, being replaced gradually by paraffin wax gum.
Paraffin gum unfortunately required the heat and moisture of the mouth to render it suitable for chewing, and was therefore replaced as a base of all "regular" gums by other substances.
Also softeners, which further retain moisture in the gum to insure a flexible, resilient chew; finally, either natural or artificial flavoring, whichever is desired, and to whatever taste, is added to the gum base in the huge mixing vats, as the giant blades slowly turn.