Libor - or London inter-bank offered rate - is used by banks to set the cost of lending money to each other.
The New York attorney-general, Eric Schneiderman said government bodies and not-for-profit organisations had been defrauded of millions of dollars.
The Libor scandal has already cost Barclays $453m.
That sum was paid to the US Justice Department, the US Commodity Futures Trading Commission and the UK's Financial Services Authority in 2012.
As part of the latest legal settlement, Barclays admitted what had already been firmly established; that some of its dealers rigged Libor rates in a system of mutual back-scratching between 2005 and 2009.
Mr Schneiderman said: "There has to be one set of rules for everyone, no matter how rich or how powerful, and that includes big banks and other financial institutions that engage in fraud or impair the fair functioning of financial markets."
Other banks that have reached settlements with the US authorities in similar Libor cases include UBS, which paid $1.5bn (£940m), RBS, Deutsche Bank and ICAP.
But Mr Schneiderman said Barclays was the first bank to settle cases brought by individual US state authorities.
For its part, Barclays said it was "pleased" to have settled this latest legal threat in the US.
"We believe this settlement is in the best interests of our shareholders and clients," it said.

Agriculture minister Barnaby Joyce said Australia had agreed to health protocols that would be finalised by his Chinese counterpart.
This comes after Indonesia slashed live cattle imports from Australia.
Mr Joyce said the trade in live cattle between Australia and China could be worth up to $A2bn ($1.5bn, Â£950m) each year.
Now that Australia had agreed on the health conditions, farmers could prepare to export cattle once China made the deal official, Mr Joyce said in a statement.
"I was very pleased today to sign the agreement of health conditions for trade of Australian feeder and slaughter cattle to Chinaâ€”now it's over to my counterpart, Minister Zhi Shuping, to sign on the dotted line and finalise the agreement between our two nations," Mr Joyce said.
"Over the past five years we've had a significant trade in breeder cattle with China, primarily for dairy heifers.
"Now, I'm pleased to announce we are a step closer to the commencement in trade in live slaughter and feeder cattle to China," he said.
Feeder cattle are those mature enough to be fattened in a feed lot before slaughter.
Earlier this month, Australian cattle producers were told Indonesia would only allow 50,000 head of cattle to be imported into the country between July and September, compared with an expected 200,000 permits for that quarter.
The Australian Livestock Exporters Council said that decision was both a surprise and a disappointment.
The Council's chief executive, Alison Penfold, said the deal with China was a "major breakthrough".
"Australia will be the first country to export feeder and slaughter cattle to China," Ms Penfold said in a statement.
In recent years, the live cattle industry has been rocked by a series of scandals about poor treatment of the animals in some of the countries Australia exports to.
Barclays bank has paid a further $100m (£77m) to settle a claim by 44 US states that it rigged the Libor rate system between 2005 and 2009.
[NEXT_CONCEPT]
Australia is a step closer to exporting live cattle to China, opening a new market for its farmers.