By Niraj Chokshi and Matthew Haag New York Times

The federal government Wednesday marked a "National Day of Mourning" for President George H.W. Bush, a recognition that coincided with his funeral. Here is a look at the day of mourning and its history.

How it was determined

President Donald Trump declared the day of mourning in a proclamation issued Saturday, a day after Bush's death. In it, Trump praised 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."

Trump also called on Americans to "pay homage" to 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, Trump ordered that the federal government shut down Wednesday, allowing federal employees to take the day off, out of respect for 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.

Some states with connections to Bush, such as Texas and Maine, also closed their government offices.

Most noticeable for most Americans will be the closing of the U.S. Postal Service. There will be no regular mail delivered Wednesday. (Some mail operations will continue to avoid disruptions to deliveries later in the week, the Postal Service said.) Both the New York Stock Exchange and the Nasdaq Stock Exchange closed. The Supreme Court was also closed, as were federal courthouses around the country and Social Security offices nationwide.

The Senate and House postponed or canceled votes to accommodate the funeral, too.

Some federal parks will be closed or have limited service, the National Park Service said, such as Acadia National Park in Maine. Mount Rainier National Park outside Seattle is open but waiving entrance fees, as is Bryce Canyon National Park in Utah. Two popular destinations in New York, the Statue of Liberty National Monument and Ellis Island, remained open, and park rangers there encouraged people to think of Bush during their visits.

"We hope our visitors can find a quiet moment to reflect on the life of public service embodied by the 41st President of the United States," officials wrote on the Statue of Liberty's website.

The history

It is common for presidents to mark the deaths of their predecessors with such proclamations: President Andrew Johnson declared a day of mourning in 1865 for Abraham Lincoln; President Richard Nixon declared one for former President Harry S. Truman in 1972; and President Bill Clinton declared one for Nixon in 1994. President George W. Bush, Bush's son, declared two while in office: one for former President Ronald Reagan and another for former President Gerald Ford.

But the recognition is not limited to the presidency. In 1968, for example, President Lyndon Johnson designated a day of mourning for the Rev. Dr. Martin Luther King Jr.

"In our churches, in our homes, and in our private hearts, let us resolve before God to stand against divisiveness in our country and all its consequences," he wrote in the proclamation.

In 1995, Clinton issued a day of mourning for those killed in the Oklahoma City bombing, writing that "good and decent people everywhere mourn the loss of innocents."

After the Sept. 11, 2001, terrorist attacks, the younger Bush declared the following Friday, Sept. 14, a national day of mourning.

"So many have suffered so great a loss, and today we express our nation's sorrow," George W. Bush said in a speech Sept. 14 at the National Cathedral, where he gathered again Wednesday for his father's funeral.