Avangrid serves about 3.1 million customers throughout New England, Pennsylvania and New York in the United States.

[5] In February 2015, Iberdrola USA announced that it had entered into a merger agreement with UIL Holdings Corporation under which UIL Holdings Corporation would merge into a subsidiary of Iberdrola USA, Inc.

[6][7] Avangrid won an auction for an offshore wind area near North Carolina by bidding $9 million in March 2017.

In 2017, Avangrid donated $2 million to the Connecticut Hydrogen and Electric Automobile Purchase Rebate program.

[11] In 2021, Avangrid's subsidiary, Central Maine Power Company, was fined $360,000 for violating standards for industry testing.