Which U.S. metro has the cleanest electric grid?

Los Angeles–Long Beach–Anaheim (CA) has the lowest grid CO2 emission rate among America's 25 largest metros at roughly 429 lbs CO2 per MWh, based on EPA eGRID 2023.

What drives a metro's grid cleanliness?

Three factors dominate: hydro share, nuclear share, and the size of the coal share. Pacific Northwest metros benefit from massive hydro; metros in MidContinent / SERC subregions with large nuclear fleets (Illinois, South Carolina) also score well; metros with significant remaining coal generation perform worst.

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Which U.S. metros have the cleanest electric grids?

Los Angeles–Long Beach–Anaheim leads at just 429 lbs of CO2 per MWh, followed by Riverside–San Bernardino–Ontario (429) and San Francisco–Oakland–Fremont (429). Average across all 25 metros: ~722 lbs/MWh — versus the coal-fired benchmark of about 2,200.

#	Metro	lbs CO2 / MWh	Marginal lbs/MWh	Nuclear %	Hydro %
1	Los Angeles–Long Beach–Anaheim(CA)	429	958	8%	14%
2	Riverside–San Bernardino–Ontario(CA)	429	958	8%	14%
3	San Francisco–Oakland–Fremont(CA)	429	958	8%	14%
4	San Diego–Chula Vista–Carlsbad(CA)	429	958	8%	14%
5	Boston–Cambridge–Newton(MA)	539	885	23%	8%
6	Charlotte–Concord–Gastonia(NC)	593	1,287	40%	1%
7	Washington–Arlington–Alexandria(DC)	597	1,176	36%	1%
8	Philadelphia–Camden–Wilmington(PA)	597	1,176	36%	1%
9	Baltimore–Columbia–Towson(MD)	597	1,176	36%	1%
10	Seattle–Tacoma–Bellevue(WA)	632	1,613	3%	39%
11	Phoenix–Mesa–Chandler(AZ)	704	1,175	18%	3%
12	Dallas–Fort Worth–Arlington(TX)	734	1,243	9%	0%
13	Houston–Pasadena–The Woodlands(TX)	734	1,243	9%	0%
14	San Antonio–New Braunfels(TX)	734	1,243	9%	0%
15	Austin–Round Rock–San Marcos(TX)	734	1,243	9%	0%
16	Miami–Fort Lauderdale–West Palm Beach(FL)	782	982	12%	0%
17	Tampa–St. Petersburg–Clearwater(FL)	782	982	12%	0%
18	Orlando–Kissimmee–Sanford(FL)	782	982	12%	0%
19	Atlanta–Sandy Springs–Roswell(GA)	842	1,386	20%	2%
20	New York–Newark–Jersey City(NY)	865	977	0%	0%
21	Chicago–Naperville–Elgin(IL)	911	1,757	28%	1%
22	Minneapolis–St. Paul–Bloomington(MN)	920	1,777	8%	4%
23	Detroit–Warren–Dearborn(MI)	971	1,508	10%	0%
24	Denver–Aurora–Centennial(CO)	1,037	1,621	0%	11%
25	St. Louis(MO)	1,240	1,819	16%	1%

How we ranked these

CO2 rates are total-output emission factors from EPA eGRID 2023 — the standard federal source for grid emission-rate accounting. The marginal column shows non-baseload rates from the same dataset: these are higher and represent the emissions you avoid by adding new clean generation today (because the marginal unit dispatched is usually a fossil plant). See full methodology.

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