Members of Marine Barracks Washington gather on the West Front of the Capitol on Inauguration Day before Donald J. Trump was sworn in as the 45th President of the United States, January 20, 2017.

Declaring a National Day of Patriotism was among Donald Trump's first acts as president of the United States, press secretary Sean Spicer said on Twitter.

@PressSec: .@POTUS signing 3 things: Mattis waiver bill into law, formal nominations 2 Senate & proclamation for nat'l day of patriotism #Inauguration

It was not immediately clear when that day would occur. There was also no immediate detail on whether this would be a presidential proclamation or a call for a federal holiday.

Presidents can declare a one-time holiday through executive order, but Congress holds the power to create annual federal holidays. In 2004, for example, George W. Bush issued an executive order for a national day of mourning following Ronald Reagan's death, shutting down the federal government for a day.

Whenever Trump's National Day of Patriotism may fall, it shouldn't be confused with previous presidential proclamations of Patriot Day.

In 2002, Bush proclaimed September 11 as Patriot Day. He first declared the day in 2001 as a National Day of Prayer and Remembrance for the Victims of the Terrorist Attacks on September 11, 2001.

In 2014, Barack Obama also proclaimed it as Patriot Day and National Day of Service and Remembrance.

Bush and Obama's presidential proclamations made September 11 a national observance, but not a federal holiday.

There are also similarly named state holidays. In Maine, Patriot's Day falls on the third Monday in April. In Massachusetts, Patriots' Day is observed on April 19.