The parade will start at 6:30 p.m., with soldiers starting their march to the parade route from the Pentagon in Northern Virginia, and heavy vehicles staged from West Potomac Park in Washington. The soldiers will then proceed to the National Mall, past the Lincoln Memorial to Mr. Trump’s review stand near the White House.

The White House and parade organizers said 250,000 people attended the June 14 event. Democratic figures and social media users disagreed.