As of 2015, most 1957 $1 silver certificates have a value of slightly more than face value, between $1.25 and $1.50. Uncirculated certificates are worth between $2 and $4. Some rare exceptions include Star notes, in which the serial number has a star after it instead of a suffix letter.
The Department of the Treasury started issuing silver certificates after Congress authorized it in 1878. The public would have the right to exchange the certificates for silver dollars. This program remained open until 1964, when the Treasury Secretary announced that the exchange program would stop. In 1967, Congress enacted a law that gave people one year (June 24, 1967 to June 24, 1968) to exchange their silver certificates for bullion.
Even though the silver certificates are no longer exchangeable for silver, they are still legal tender, and people can spend them just like they would spend a Federal Reserve note. The most valuable $1 silver certificates are the 1935A Hawaii and North Africa notes. The most valuable certificates exchangeable for precious metals are the $500 and $1000 gold certificates that were issued in 1928. Their scarcity gives them a significantly higher value than the lower-denomination 1928 gold certificates and all series of silver certificates.