Yes, they can be found in circulation.
Yes, 1981 100 dollar bills are still considered legal tender and can be used in circulation. However, they may be less commonly seen due to their age, as newer designs of the 100 dollar bill have been introduced since then. It's always a good idea to check with banks or businesses to ensure they will accept older bills.
The banner across its top and the green seals on your bills indicate they're Federal Reserve Notes. The last US silver certificates were $1 bills dated 1957.That said, because $100 bills last longer in circulation, anything dated 1981 or 1985 is still only worth face value in average condition.
They were minted for circulation in 1979 and 1980, for collectors in 1981, and again for circulation in 1999.
Older $50 bills didn't get as much use because that was a significant amount of money 3 decades ago, so it's possible that some are still in circulation. In any case, the government has never withdrawn any Federal Reserve Notes from circulation nor do they keep track of specific bills. Individual bills are returned for destruction only when a bank receives them and sorts out those that are too worn for further use. Bottom line, there's no way to be 100% certain how many remain.
Series 1981 $100 bills have the signatures of Treasury Secretary Donald Regan and US Treasurer Angela Buchanan. Series 1981 A bills were issued when Buchanan was replaced by Katherine Ortega.
Only in proof and mint sets. None for circulation.
From your description the coin is a common Susan B. Anthony dollar (1979-1981 & 1999) that is in circulation today. It's just a dollar coin, spend it.
1979, 1980, and 1999 for circulation, and 1981 (mint set issue only)
Security strips were first used in 1990. They were added to all denominations except $1 and $2 bills.
The only U.S. one dollar coin dated 1981 is a Susan B. Anthony dollar. They are not referred to as Liberty Dollars. None were released into circulation or made from gold. It's been gold plated. Look at the coin again and post new question.
Unless your bill was hand-autographed separately, all bills carry facsimiles of the signatures of the Secretary and Treasurer in office at their time of issue. So many dollar bills are printed each year that they rarely have any extra value unless they are preserved in new, unfolded condition. If yours is from circulation, feel free to spend it on a soda or Sunday paper.
No Dollar coins were struck for circulation in the years of: 1793-1804 to 1839/1905 to 1920/ 1929 to 1933/ 1936 to 1970/ 1981 to 1998: Note: The 3 years of 1836-1839 Gobrecht Dollars were struck but did not circulate because of the changing weight standard for dollar coins. Also the 1981 SBA dollar was struck but was not released for circulation, it was a mint set issue only coin.
The US didn't print any $100 bills with that date. In any case, $100 bills get less wear than most other denominations so anything dated 1981 or later that's been in circulation is only worth face value. Even uncirculated, they only sell for $100 to $105.