It was unclear how the markings in the grass were made. In some areas, the grass turned brown to form the shape of numbers in contrast to the surrounding green.
The US Park Police said the cause of the “discolouration” has not yet been determined. A spokesperson said grass samples have been collected for testing and an investigation is ongoing.
The White House referred questions about the incident to the Department of the Interior. The incident comes as the National Mall is set to be the scene for events celebrating the 250th anniversary of US independence in the coming weeks.
Trump has devoted personal attention to refurbishing the space, including painting the reflecting pool near the Lincoln Memorial. A 16-day Great American State Fair is set to take place on the National Mall beginning on Jun 25.
The term “8647” is at the centre of at least one high-profile criminal case. Federal prosecutors charged former FBI Director James Comey with threatening Trump based on a photo he posted on social media in 2025 showing seashells on a beach arranged to form the numbers “8647”.
Comey took down the post and said he was not aware it could be interpreted as a call to violence. He has vowed to fight the charges, including on free speech grounds.
A federal judge ruled earlier this month that the National Park Service could not prevent an anti-Trump protest group from displaying an “8647” flag near the National Mall.