The Environmental Protection Agency said Monday it will tighten pollution standards for cars and light trucks in an attempt to reduce carbon dioxide emissions from automobiles.

Why it matters: Transportation overall is the largest source of U.S. greenhouse gas emissions, so tougher standards for passenger vehicles are a major part of efforts to curb CO2 output.

By the numbers: The new rules will require passenger vehicles to travel an average of 55 miles per gallon of gasoline by 2026.

• The EPA said this new standard will prevent around 3 billion tons of greenhouse gas emissions by 2050, which it said is equivalent to more than half the total U.S. CO2 emissions in 2019.
• The rules will go into effect 60 days after it is published in the Federal Register.

Thought bubble, via Axios' Ben Geman: The standards through the middle of the decade have been a long and winding saga. Former President Obama initially set them, but they were then weakened by former President Trump.

• Now Biden is restoring that effort with regulations that exceed the Obama-era plan and is signaling that he wants to go much further in subsequent years.

What they're saying: “The final rule for light duty vehicles reflect core principles of this Administration: We followed the science, we listened to stakeholders, and we are setting robust and rigorous standards that will aggressively reduce the pollution that is harming people and our planet — and save families money at the same time,” EPA chief Michael Regan said in a statement.

• “We applaud the EPA for listening to the public and the climate science and acting swiftly to strengthen the federal clean car standards, our nation’s most powerful tool to slash emissions,” Sierra Club president Ramón Cruz said in a statement.

The big picture: President Biden signed an executive order earlier this month that requires the federal government to become carbon neutral by 2050.

• As part of the order, the government will be required to stop buying gas-powered vehicles by 2035.

Go deeper: How the Biden climate agenda could be rescued after Manchin stunner