Since the tradition of a State of the Union address began in the late 18th century, only a few presidents have not delivered their final speech in person.

Harry Truman, Dwight D. Eisenhower and Jimmy Carter all sent written copies of their speeches to Congress. Barack Obama doesn’t want to be No. 4.

Instead, he will deliver his final State of the Union address at the Capitol on Tuesday, about a week earlier than usual.

“Since I took office seven years ago in the midst of crisis, I don’t think I’ve ever been more optimistic about a year ahead than I am right now,” Obama said in a video previewing the speech.

Some questions and answers about the State of the Union address:

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Q: Why is the president giving the speech?

A: The Constitution requires that the president “from time to time give the Congress information on the State of the Union, and recommend to their consideration such measures as he shall judge necessary and expedient.”

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Q: Who delivered the first State of the Union address?

A: George Washington on Jan. 8, 1790 in New York.

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Q: Does it have to be a speech?

A: No. For his first address on Dec. 8, 1801, Thomas Jefferson sent written copies to both houses of Congress to be read by each chamber’s clerks. Jefferson wanted to simplify what he believed was an aristocratic imitation of the British monarch’s speech from the throne, which he thought ill-suited for a republic. The practice of sending written copies to Congress continued for more than a century.

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Q: Who resumed delivering the annual message in person?

A: Woodrow Wilson, on April 8, 1913. He’s also credited with transforming the speech from a report on executive branch activity into a blueprint for the president’s legislative agenda for the year.

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Q: When did the annual message become known as the “State of the Union” address?

A: Franklin D. Roosevelt applied the constitutional phrase “State of the Union” to both the message and the event. It became the popular terminology from then on.

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Q: How has the speech been affected by advances in communications technology?

A: Calvin Coolidge delivered the first speech broadcast on radio in 1923. Harry Truman’s address in 1947 was the first broadcast on television. Lyndon B. Johnson recognized the importance of having a national audience when he moved the speech from midafternoon to 9 p.m. in 1965 to attract the largest number of TV viewers. George W. Bush’s 2002 speech was the first available as a live webcast on the White House website.

Obama used social media to help power his presidential campaigns, and he’s used Twitter, Facebook, Tumblr, Instagram and YouTube to promote his State of the Union addresses. Obama devotes a page on the White House website to the speech. This year, the White House is using the online annotation platform Genius to revisit Obama’s past State of the Union speeches by adding context and commentary. It’s also using Snapchat and Amazon Video to bring Tuesday’s address to the “people where they are.”

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Q: Has the speech ever been postponed?

A: Ronald Reagan’s 1986 address was postponed after the Challenger space shuttle exploded in flight on Jan. 28 of that year.

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Q: Is there a State of the Union speech every year?

A: No. Each of the past five presidents — Reagan in 1981, George H.W. Bush in 1989, Bill Clinton in 1993, George W. Bush in 2001 and Obama in 2009 — chose not to give an official State of the Union address their first year in office. That speech would have come soon after their inaugural addresses.

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Q: Has the State of the Union speech always been delivered in person since Wilson resumed the practice?

A: No. Truman sent his final message in print, as did Eisenhower in 1961 and Carter in 1981. As Eisenhower recovered from a heart attack in 1956, he prepared a seven-minute, filmed summary of the message from his retreat in Key West, Florida, that was broadcast nationwide. Richard Nixon sent a printed message in 1973; his staff said an oral message would have come too soon after his second inaugural address.

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Q: Which presidents didn’t deliver a State of the Union message?

A: William Henry Harrison, who died 32 days after his inauguration in 1841, and James A. Garfield, who was assassinated in 1881 after 199 days in office.

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Q: Who sits with the first lady?

A: The White House invites people whose personal stories help highlight a particular issue or public policy. Reagan was the first in 1982 to invite special guests and recognize them during the speech. Every president since has continued the tradition. With gun violence drawing increased attention from Obama, one seat in Michelle Obama’s guest box will be left empty in memory of victims of gun violence, the White House said.

(AP)