Sixteen states and the District of Columbia want the U.S. Postal Service to buy electric-powered delivery vehicles.
They're suing to halt purchases of thousands of gas-powered trucks.
Three lawsuits were filed Thursday in New York and California by the states and environmental groups.
They're demanding the Postal Service conduct a more thorough environmental review before moving forward with the next-generation vehicle program.
They claim that the USPS underestimated the toll the trucks would take on the environment, according to the Washington Post.
They also claim the Postal Service miscalculated the cost of the vehicles.
The Postal Service’s fleet includes 190,000 local delivery vehicles, most of which went into service between 1987 and 1994.
The Postal Service plans to buy up to 165,000 new vehicles over the next 10 years.