American International Group Inc. said it has closed the sale of 21st Century Insurance Group to Farmers Group Inc. for $1.9 billion.

The 21st Century Insurance business, based in Los Angeles, was a subsidiary of AIG’s U.S. personal auto insurance division. Farmers Group, also based in Los Angeles, is a subsidiary of the Zurich Financial Services Group in Switzerland.

21st Century Insurance has 2.4 million customers and brought in $3.6 billion in premiums in 2008.

The deal, part of part of troubled AIG’s restructuring efforts, includes $1.7 billion in cash and $200 million in subordinated, Euro-dominated capital notes backed by Zurich Insurance Co. Farmers also assumes 21st Century’s outstanding debt of $100 million.