quote:
Are they still legal tender and spendable?
Some of them were legal tender, the United Colonies, United States, and the guaranteed issue of 1780, but they were not worth much when they were circulating giving rise to the saying:
"Not worth a Continental" because the government issuing them was shaky, these were promissory notes with no practical or real backing ie Spanish milled dollars" etc. despite what is noted on the note:


They stopped circulating for all practical purposes after 1782, but people held onto them in the hopes of redemption. The government made good on them in 1790, but only for bonds that paid 1¢ on the dollar, so holders of these notes found them for all reality valueless. The bonds were only payable after 1815, and many were not subsequently paid out.
The State or Colony issues were never paid out, they lost all value.
So no, no US paper money issued before 1861, and some issued after that date is not legal tender.