[2] Established in 1900, North Shore Natural Gas grew into the natural gas delivery supplier to approximately 158,000 residential, commercial, and industrial customers in 54 communities in the north-suburban area of Chicago in Lake County.

Integrys also owns and operates regulated and non-regulated energy businesses in Michigan, Minnesota and Wisconsin.

In February 2008, the Illinois Commerce Commission granted a controversial Peoples Gas/North Shore Gas request for a customer delivery rate increase.

The approval, settled at $71 million, was expected to increase the average monthly customer gas bill by $7, or 4% to 5%.

[citation needed] In 2015, Integrys was acquired by, and became a subsidiary of WEC Energy Group.