Editor's Note: This article was updated in August 2021 to reflect the latest data. 

As major global greenhouse gas (GHG) emitters, U.S. states have the economic heft and legislative authority to move the United States toward much lower emissions and cleaner energy. While many have done so in the last decade, some remain stuck in the high-emitting past.

The following eight charts show how emissions from U.S. states compare, how they are changing and what could come next. These are based on the latest greenhouse gas emissions data World Resources Institute compiled for all 50 states and the District of Columbia (through 2018, the latest year for which state-level emissions data are available).

1. The Top 10 Emitting States Contribute Half of U.S. Total Emissions

In 2018, the top 10 emitting states were responsible for nearly half of the country’s total GHG emissions, nearly equal to the combined emissions of Japan, Canada and Germany, or all of India’s emissions. The top emitters included Texas, California, Florida, Illinois, Pennsylvania, Ohio, Louisiana, Indiana, New York and Michigan. Click around on the interactive chart to explore the emissions profile for each state.

Note that the interactive chart (#1) and the donut chart (#2) do not include emissions or removals from the land sector, as they cannot display negative values. The remaining charts (#3, #4 and #5) and corresponding analysis include all sources of emissions.

2. The U.S. Energy Sector Contributes 84% of the Country’s Total Emissions

In 2018, the energy sector contributed to about 84% of total U.S. greenhouse gas emissions, with the sub-sectors transportation (29%) and electric power (26%) being the top two contributors.

3. Texas and California Are the Biggest U.S. State Emitters of the Past Ten Years

Texas and California[1] are first and second top state emitters, respectively, and have been more than 50% higher than the third-largest emitter for more than a decade. This comes as no surprise since both rank in the top two for population and economic size — two important driving forces of emissions.

Lower down in the list, though there are changes in the specific ranking of the states, the three clusters of emissions trends have been clear and stable over the years. For more than ten years, New York and Michigan have been ranked as number nine and number 10, while the other six states have fluctuated within the top three to eight (with emissions between 200 to 300 MtCO2e).

It’s important to note that these rankings are based on values calculated with a certain set of methodologies and data sources. As a result, these values could differ from those reported by their respective states.

4. Wyoming and North Dakota Are the Most Emissions-intensive States by GDP and Per Capita

The story changes when looking at states’ emissions through the lens of emissions intensity — GHG per GDP and GHG per capita. In both cases, the top emitters are Wyoming and North Dakota, followed by West Virginia. Emissions from those states are due mostly to electricity generation. After that, the individual rankings depend on whether the emissions intensity is based on GDP or population. Regardless, there is considerable overlap among the top 10 list for emissions intensity expressed both for their levels of emissions per person and per unit of GDP, with nine states appearing on both lists.

Louisiana is also the only state that ranks in the top 10 in emissions per unit of GDP, per person and in the absolute amount of total emissions. Interestingly, the state ranks high neither in terms of population size nor GDP size: it accounts for only around 1% of the total U.S. population and total U.S. GDP. Key factors driving this include Louisiana’s abundant fossil fuel resources and an emissions-intensive industrial sector that accounts for a major share of the country’s oil refining and natural gas production capacity. Illustrating this, energy use in Louisiana’s industrial sector contributed to more than half of its total GHG emissions.

New York, the fourth most populous U.S. state, is one of the country’s lowest per capita emitters. Since 2005, its electricity and heat emissions have fallen by more than 55% as a result of a range of state-level energy policies that promote efficiency and renewables (such as the Regional Greenhouse Gas Initiative), as well as shifting market forces.

5. 38 States Are Dropping Their Emissions

Overall, U.S. emissions declined by 9% from 2005 to 2018. The story varies, however, on a state basis.

Thirty-eight states and Washington, D.C. reduced their emissions from 2005 to 2018, with Maine, New Hampshire and Alabama leading the way. Maine benefits from vast forestland that acts as a carbon sink to absorb more carbon dioxide than it releases. The state also saw emission reductions in the industry sector, which was caused by the declining share of traditional energy-intensive industries and growing service industries like finance, insurance, real estate, health care and tourism. In contrast, New Hampshire and Alabama’s reductions came largely from the clean electricity and heat sector.

Twelve states have increased their emissions, with Mississippi, North Dakota and Idaho in the lead. North Dakota’s increase was primarily driven by surging shale gas production and a lack of standards that require operators to adopt all cost-effective measures for controlling methane emissions.

In nearly the same timeframe, 41 states reduced their CO2 emissions while growing their economies, proving that climate action and economic prosperity go hand-in-hand.

6. Emissions from Electricity, Residential and Transportation Sectors Are in Decline, While Commercial Building Emissions Remain a Challenge

Nearly all states have reduced emissions from the electric power sector, with Ohio, Pennsylvania and Georgia recording the largest reductions. According to the latest EIA data, the switch from coal-fired power plants to natural gas-fired electricity generation has been one of the leading factors contributing to those reductions: all three states have halved their electricity generation from coal over the past decade.

Most states have also cut emissions from residential buildings and transportation. California, whose transportation sector is the largest contributor to its GHG emissions, has led the pack by significantly reducing fuel use overall with its efforts to transition to a clean transportation sector. In contrast, Texas has seen an increase in its transport-related emissions because of the rise in diesel fuel, motor gasoline and jet fuel consumption. However, California and Texas both saw the largest increases in emissions from commercial buildings, leading California to call for progressively increasing the stringency of building codes and standards

With Enhanced Federal Leadership, States Should Continue Stepping Up

Two months after the United States rejoined the Paris Agreement, the nation committed to reduce greenhouse gas emissions 50% to 52% below 2005 levels by 2030 in its new national climate commitment (known as a nationally determined contribution, or NDC). While it is encouraging to see the enhanced federal leadership to address climate change issues, subnational actors such as state and local governments play an essential role in reducing emissions, and the momentum should continue.

Subnational governments can not only enable more ambitious federal policies over time, but are typically in the best position to implement action, such as making planning and zoning decisions for local land use, finding local transportation solutions and allocating funding to address climate change in an equitable manner. The Biden administration’s American Jobs Plan outlined major investments to combat climate change while also creating jobs and spurring economic growth. If implemented, these investments could help create thousands of jobs and boost local economies, especially in rural communities that have been hard hit by the economic downturn and years of decline. The investments would also enable states to take further climate action, which will be essential to meet the nation’s emissions reduction goals.

Please Note: The State level greenhouse gas emissions estimates in the interactive chart are calculated based on the State Inventory Tool released by the U.S. EPA. Climate Watch data are compiled using a consistent methodology and comparable across states, and might differ from State-reported inventories. Aggregating state level emissions data might differ from the national level estimate of emissions due to differences in methodology and data sources. Aside from the interactive chart, or unless otherwise specified, all emissions data presented here cover all sectors (including land sector emissions) and all greenhouse gases. The land sector emissions cannot be reflected in the interactive chart due to the existence of negative values.

[1] The values here could be different from the states reported values (for example, California's state reported inventory) because of different methodologies and data sources.