The federal government on Wednesday marked a “National Day of Mourning” for President George Bush, a recognition that coincided with his funeral. Here’s a brief look at the day of mourning and its history.

[Here are the highlights of Mr. Bush’s funeral in Washington.]

How it was determined

President Trump declared the day of mourning in a proclamation issued on Saturday, a day after Mr. Bush’s death. In it, Mr. Trump praised Mr. Bush’s humility and “unselfish spirit,” and ordered the flag of the United States to be flown at half-staff for 30 days “as an expression of public sorrow.”

Mr. Trump also called on Americans to “pay homage” to Mr. Bush’s memory on that day and invited “the people of the world who share our grief to join us.”

What it means — here’s what’s closed

In issuing his proclamation, Mr. Trump ordered that the federal government shut down on Wednesday, allowing federal employees to take the day off, out of respect for Mr. Bush. But it does not apply to everyone. People employed in the areas of national security, defense and “other essential public business” are not excused, according to a federal memo sent to government agencies and departments.