A U.S. Postal Service (USPS) logo is pictured on a mail box in the Manhattan borough of New York City, New York, U.S., August 21, 2020.
A U.S. Postal Service (USPS) logo is pictured on a mail box in the Manhattan borough of New York City, New York, U.S., August 21, 2020. Reuters / CARLO ALLEGRI

Sixteen states, four environmental groups and the United Auto Workers union filed suits on Thursday seeking to block a U.S. Postal Service (USPS) plan to buy mostly gas-powered next-generation delivery vehicles, arguing that the agency failed to comply with environmental regulations.

Three separate lawsuits were filed in federal courts in San Francisco and New York City, also naming U.S. Postmaster General Louis DeJoy as a defendant.

The states, led by Democratic-led New York and California, were joined by the District of Columbia and New York City in a suit accusing USPS of using a flawed and unlawful environmental analysis and signing contracts before even completing a draft environmental review.

USPS "is doubling down on outdated technologies that are bad for our environment and bad for our communities," said California Attorney General Rob Bonta, a Democrat.

CleanAirNow, the Center for Biological Diversity and the Sierra Club also sued, as did the UAW and the Natural Resources Defense Council.

In response to the lawsuits, USPS said it has "conducted a robust and thorough review and fully complied with all of our obligations under" environmental law.

USPS last month said it had placed an initial $2.98 billion order for 50,000 next-generation delivery vehicles from Oshkosh Corp - and had doubled its planned electric vehicle purchases from 5,000 to 10,019. USPS has said it could buy up to 165,000 vehicles over 10 years.

The White House and Environmental Protection Agency (EPA) have also asked USPS to reconsider, as have many Democrats in Congress.

USPS has said it expects the vehicles will begin appearing on carrier routes in late 2023. The modern vehicles will replace many 30-year-old USPS ones that lack air bags and other safety equipment as well as air conditioning.

The UAW and many U.S. lawmakers have criticized USPS and Oshkosh for opting to build the vehicles in South Carolina with non-union workers rather than at a UAW-represented facility in Wisconsin.

DeJoy, a supporter of former President Donald Trump, was named as postmaster general in 2020 by the Postal Service's governing board.