In a joint filing with the Illinois Commerce Commission today, Southern Company and AGL Resources requested regulatory approval of the companies' proposed merger.

AGL Resources is the parent company of Nicor Gas, a regulated utility providing natural gas services to approximately 2.2 million customers in northern and central Illinois. 

When completed, the combination of Southern Company and AGL Resources is expected to create the second-largest utility company in the U.S. by customer base, bringing together:

• 11 regulated electric and natural gas distribution companies providing service to approximately nine million customers;

• Operations of nearly 200,000 miles of electric transmission and distribution lines;

• More than 80,000 miles of gas pipelines; and

• Approximately 46,000 megawatts of electricity generating capacity.

The companies expect to complete the transaction in the second half of 2016.