20 Dollars

The Bank of Yarmouth was a small Nova Scotia chartered bank that operated from 1859 until 1869, when it wound up its affairs — a lifespan short enough that its notes in any denomination are genuinely uncommon today. The American Bank Note Company produced the plates in New York, which was standard practice for Maritime Canadian banks of the period; local printing infrastructure simply couldn't match the security engraving quality ABNCo offered.

At the twenty-dollar level, demand was low relative to smaller denominations, and fewer were printed to begin with. The bank's failure within a decade means redemption and destruction reduced surviving numbers further.