WASHINGTON (AP) — Nearly 400 school districts spanning all 50 states and Washington, D.C., along with several tribes and U.S. territories, are receiving roughly $1 billion in grants to purchase about 2,500 "clean" school buses under a new federal program.

The Biden administration is making the grants available as part of a wider effort to accelerate the transition to zero-emission vehicles and reduce air pollution near schools and communities.

Vice President Kamala Harris and Environmental Protection Agency Administrator Michael Regan are set to announce the grant awards Wednesday in Seattle. The new, mostly electric school buses will reduce greenhouse gas emissions, save money and better protect children's health, the White House said.

As many as 25 million children ride familiar yellow school buses each school day and will have a "healthier future" with a cleaner fleet, Regan said. "This is just the beginning of our work to ... reduce climate pollution and ensure the clean, breathable air that all our children deserve," he said.

Only about 1% of the nation's 480,000 school buses were electric as of last year, but the push to abandon traditional diesel buses has gained momentum in recent years. Money for the new purchases is available under the federal Clean School Bus Program, which includes $5 billion from the bipartisan infrastructure law President Joe Biden signed last year.

The clean bus program "is accelerating our nation's transition to electric and low-emission school buses while ensuring a brighter, healthier future for our children," Regan said in a statement.

The EPA initially made $500 million available for clean buses in May but increased that to $965 million last month, responding to what officials called overwhelming demand for electric buses across the country. An additional $1 billion is set to be awarded in the budget year that began Oct. 1.

The EPA said it received about 2,000 applications requesting nearly $4 billion for more than 12,000 buses, mostly electric. A total of 389 applications worth $913 million were accepted to support purchase of 2,463 buses, 95% of which will be electric, the EPA said. The remaining buses will run on compressed natural gas or propane.

School districts identified as priority areas serving low-income, rural or tribal students make up 99% of the projects that were selected, the White House said. More applications are under review, and the EPA plans to select more winners to reach the full $965 million in coming weeks.

Districts set to receive money range from Wrangell, Alaska, to Anniston, Alabama; and Teton County, Wyoming, to Wirt County, West Virginia. Besides Washington, major cities that won grants for clean school buses include New York, Dallas, Houston, Atlanta and Seattle.

Environmental and public health groups hailed the announcement, which comes after years of advocacy to replace diesel-powered buses with cleaner alternatives.

"It doesn't make sense to send our kids to school on buses that create brain-harming, lung-harming, cancer-causing, climate-harming pollution,'' said Molly Rauch, public health policy director for Moms Clean Air Force, an environmental group. "Our kids, our bus drivers and our communities deserve better.''

Harris and Regan are expected to announce the awards at an event in Seattle with Sen. Patty Murray, D-Wash., and Gov. Jay Inslee. Murray is running for reelection against Republican Tiffany Smiley.