JFK actually minted competing currency, Red seal “u s treasury” notes.
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Wow. I didn’t know that. I’m learning more every day. Thank you for adding to my education. :)
In 1963 there were three issues of US paper currency- Silver Certificates, U.S. Notes, and Federal Reserve Notes.
The Silver Certificates could be exchanged for silver coin.
The U.S. Notes were Lincoln's Civil War Greenback issue- that issue of fiat currency had been carried forward since the day it was authorized.
Federal Reserve Notes were paper money that didn't belong to either of the other two note issues.
The Red Seal notes of 1963 were all $5 bills, and they were in fact the U.S. Note issue mentioned above. They originated with Lincoln, not JFK.
Moreover JFK was the driving force for getting rid of both Silver Certificates and silver American coinage. You can read his own words on the subject in his 1963 Economic Report to Congress, beginning on page XXIII:
http://www.presidency.ucsb.edu/economic_reports/1963.pdf