SEGMENT INFORMATION

We use operating income to measure segment profitability and to allocate resources to our businesses. At March 31, 2019, we reported six segments, which are described below.


•	The Wisconsin segment includes the electric and natural gas utility operations of WE, WG, WPS, and UMERC.


•	The Illinois segment includes the natural gas utility and non-utility operations of PGL and NSG.


•	The other states segment includes the natural gas utility and non-utility operations of MERC and MGU.

•

The electric transmission segment includes our approximate 60% ownership interest in ATC, a for-profit, transmission-only company regulated by the FERC for cost of service and certain state regulatory commissions for routing and siting of transmission projects, and our approximate 75% ownership interest in ATC Holdco, which invests in transmission-related projects outside of ATC's traditional footprint.

•

The non-utility energy infrastructure segment includes We Power, which owns and leases generating facilities to WE, Bluewater, which owns underground natural gas storage facilities in Michigan that provide approximately one-third of the current storage needs for our Wisconsin natural gas utilities, our 90% membership interest in Bishop Hill III, a wind generating facility located in Henry County, Illinois, our 80% membership interest in Coyote Ridge, a wind generating facility under construction in Brookings County, South Dakota, and our 80% membership interest in Upstream, a wind generating facility located in Antelope County, Nebraska. See Note 2, Acquisitions, for more information on Bishop Hill III, Coyote Ridge, and Upstream.


•	The corporate and other segment includes the operations of the WEC Energy Group holding company, the Integrys holding company, the Peoples Energy, LLC holding company, Wispark LLC, Wisvest LLC, Wisconsin Energy Capital Corporation, WEC Business Services LLC, and WPS Power Development, LLC.

All of our operations are located within the United States. The following tables show summarized financial information related to our reportable segments for the three months ended March 31, 2019 and 2018:



	Utility Operations
(in millions)	Wisconsin		Illinois		Other States		Total Utility Operations		Electric Transmission		Non-Utility Energy Infrastructure		Corporate and Other			Reconciling Eliminations			WEC Energy Group Consolidated
Three Months Ended
March 31, 2019
External revenues	$	1,633.4	$	536.5	$	185.2	$	2,355.1	$	—	$	20.6	$	1.7		$	—		$	2,377.4
Intersegment revenues	—		—		—		—		—		107.2		—			(107.2		)	—
Other operation and maintenance	392.7		128.2		27.6		548.5		—		3.8		(1.0		)	(0.7		)	550.6
Depreciation and amortization	151.0		44.5		6.5		202.0		—		22.6		6.4			(4.6		)	226.4
Operating income (loss)	361.8		137.9		41.5		541.2		—		92.7		(3.9		)	(87.2		)	542.8
Equity in earnings of transmission affiliates	—		—		—		—		36.1		—		—			—			36.1
Interest expense	143.4		14.8		2.3		160.5		2.6		15.7		35.1			(89.5		)	124.4



	Utility Operations
(in millions)	Wisconsin		Illinois		Other States		Total Utility Operations		Electric Transmission		Non-Utility Energy Infrastructure		Corporate and Other			Reconciling Eliminations			WEC Energy Group Consolidated
Three Months Ended
March 31, 2018
External revenues	$	1,589.1	$	507.3	$	169.9	$	2,266.3	$	—	$	18.8	$	1.4		$	—		$	2,286.5
Intersegment revenues	—		—		—		—		—		99.3		—			(99.3		)	—
Other operation and maintenance	468.5		112.2		26.6		607.3		—		1.7		(0.3		)	(96.8		)	511.9
Depreciation and amortization	135.1		40.9		6.6		182.6		—		18.3		7.7			—			208.6
Operating income (loss)	273.7		147.6		36.2		457.5		—		93.0		(5.4		)	—			545.1
Equity in earnings of transmission affiliates	—		—		—		—		32.8		—		—			—			32.8
Interest expense	49.4		12.3		2.1		63.8		—		16.1		28.0			(1.2		)	106.7