Why is there a red seal on a 1963 US 2 dollar bill?

Answer 1

Red seals were the standard color indicating that a bill was a United States Note, a form of currency discontinued in the late 1960s. Other colors included blue for silver certificates, gold for gold certificates, and yellow and brown for special wartime bills.

From 1928 to 1963 all $2 and many $5 bills were US Notes. They differ from Federal Reserve Notes in that they represented a direct financial obligation of the US government itself rather than an indirect one through the Federal Reserve Bank.

In practice the difference was more theoretical than practical, so the two types of bills were consolidated to reduce the costs associated with printing and accounting for two different forms of paper money.