US Notes were discontinued in 1966. These bills were a parallel series to Federal Reserve Notes and served no distinct purpose, so the Treasury decided it would be more economical to simply issue one type of currency.
US Notes are distinguishable by their red ink. In reality, most of them were issued as higher denominations - the last $1 US Note was dated 1928. $5 ones were printed up through the 1963 series and $100 bills up through 1966.
No denomination of coin or bill was discontinued in 1966. You may be thinking of the printing of United States Notes, which were a form of currency that circulated along with Federal Reserve Notes. US Notes were distinctive because their seals and serial numbers were printed in red ink, rather than green. They were printed in much smaller numbers than FRN's and served the same purpose, so they were discontinued as a cost-saving measure effective with the 1966 series of $100 bills.
There weren't any printed with that date.
The $2 bill has never been discontinued in the US. The most recent printing is the 2013 series.
The red seal as well as the banner across the top of Franklin's portrait indicate your bill a United States Note and not a silver certificate. Please see the question "What is the value of a 1966 US 100 dollar bill?" for more information.
The blue seal indicates your bill is a silver certificate, a form of paper money that was discontinued in the early 1960s. Please see the question "What is the value of a 1934 US 5 dollar silver certificate?" for more information.
The US twenty dollar bill has not been discontinued.
Please don't assume that every old bill is a silver certificate. The banner across its top and the red seal indicate it's a United States Note, a form of paper money issued directly by the Federal government. US Notes were discontinued in the 1960s. There's more information at the question "What is the value of a 1966 A US 100 dollar bill?".
No denomination of coin or bill was discontinued in 1966. You may be thinking of the printing of United States Notes, which were a form of currency that circulated along with Federal Reserve Notes. US Notes were distinctive because their seals and serial numbers were printed in red ink, rather than green. They were printed in much smaller numbers than FRN's and served the same purpose, so they were discontinued as a cost-saving measure effective with the 1966 series of $100 bills.
There weren't any printed with that date.
The $2 bill has never been discontinued in the US. The most recent printing is the 2013 series.
The red seal as well as the banner across the top of Franklin's portrait indicate your bill a United States Note and not a silver certificate. Please see the question "What is the value of a 1966 US 100 dollar bill?" for more information.
A red seal on any US bill dated 1928 to 1966 indicates that it's a United States Note, a form of currency printed from 1862 to the late 1960s. US Notes were a kind of parallel currency that circulated alongside FRN's until they were discontinued to reduce the overhead of printing multiple types of bills. For values, please see the question "What is the value of a 1953 US 5 dollar bill with a red seal?" for more information.
It's a 1966 A $100 Red Seal Elston/Kennedy bill, nothing more.
Please check again and post a new question. The US didn't print any bills dated 1968. The last $2 red seal notes were printed in the 1963 series, and all US Notes were discontinued as of the 1966 series of $100 bills.
The blue seal indicates your bill is a silver certificate, a form of paper money that was discontinued in the early 1960s. Please see the question "What is the value of a 1934 US 5 dollar silver certificate?" for more information.
Please check again and post a new, separate question. There are no US $2 bills with that date
Irish people call the US Dollar bill, a dollar or a dollar bill.