Hi Sherrie. There is no really definitive answer. Some dulcimers in the late or mid-1800s had a 6 1/2 fret, but no seventh fret. Regular use of the 6 1/2 fret probably began in the mid-to-late 1960s. The 1 1/2 fret has been around for quite a while as well. It has gained more popularity in recent years. I think we have discussed this in the History of the Dulcimer forum. You can look in that forum or do a search.
Ken
"The dulcimer sings a sweet song."
updated by @ken-longfield: 02/12/16 01:03:28AM
