The White House and U.S. Postal Service have finalized plans for a pilot program to deliver 500 million coronavirus testing kits to American households, according to an agreement between the USPS and American Postal Workers Union.

Postal workers at 43 facilities across the United States, including Philadelphia, Harrisburg, and Pittsburgh, will build and label millions of testing kits for mail delivery, according to the agreement.

President Joe Biden’s administration has built a website, covidtests.gov, where, beginning Jan. 19, each American household can request up to four testing kits to be delivered. The site, which launched Friday, says “the tests will be completely free — there are no shipping costs and you don’t need to enter a credit card number.”

Andy Kubat, president of the Lehigh Valley area APWU, who was on a union teleconference call Thursday when plans for the program were presented, said it’s anticipated the USPS could deliver upward of 2 million kits per day.

“I heard some offices are reporting there are pallets of kits already there, or at least components of the kits,” Kubat said.

In Philadelphia, the tests will be stored, built, and shipped out of a nearly 120,000-square-foot warehouse in Upper Chichester Township in Delaware County, which the USPS leased in November for five years for package overflow, said Philly APWU Local 89 president Nick Casselli.

Casselli said he expects to get more information about the plans and shipments of the kits on Friday.

The pilot program will last 75 days from Jan. 12, according to the agreement, which was signed Wednesday by national APWU president Mark Diamondstein and USPS vice president of labor relations Katherine Attridge.

Deputy press secretary Karine Jean-Pierre told reporters last Friday that the Biden administration was “actively finalizing the details of the distribution mechanism, including a website,” and that the kits would be sent through the mail.

On Thursday, Biden announced that the government would purchase an additional 500 million tests to prepare for future surges — meaning, in total, the government will provide 1 billion free tests.

The USPS declined to comment on specifics of the plan, and deferred to the White House, which could not be immediately reached for comment.

Postmaster General Louis DeJoy has said in a statement that the Postal Service was “proud to fulfill its mission of service” by delivering the tests.

“The 650,000 women and men of the United States Postal Service are ready to deliver and proud to play a critical role in supporting the health needs of the American public,” DeJoy said. “We have been working closely with the administration and are well prepared to accept and deliver test kits on the first day the program launches.”

The delivery comes as coronavirus cases surge to unprecedented levels in the United States amid the highly contagious omicron variant. The demand for testing amid the surge greatly outpaced those available, with Americans across the country, including Philadelphians, waiting in hours-long lines for tests during the holidays, or being unable to find or book testing appointments at all.

“The Postal Service wants to move on this quickly because the need is there,” Kubat said.

Editor’s note: This story was updated Friday to include new information from the White House about the testing website.