Why should you watch President Obama's State of the Union address Tuesday evening? In a video released by the White House, chief of staff Denis McDonough makes the case: "It is an important moment when the policy that influences the fabric of the American experiment is shaped." Never mind that Obama will be trotting out many of the same agenda items as last year, ideas Congress blocked or ignored. Let's dispense with some myths about the speech and its importance.

1. The State of the Union must be delivered orally to Congress each year.

The Constitution requires that the president "from time to time give to the Congress Information on the State of the Union, and recommend to their Consideration such Measures as he shall judge necessary and expedient." George Washington established the yearly precedent when he delivered his "First Annual Message to Congress on the State of the Union" on Jan. 8, 1790. Although Washington presented his message in person, that aspect of the tradition was quickly killed by Thomas Jefferson, who was uncomfortable with public speaking and rationalized that giving "a speech from the throne" was too like a monarch. Jefferson sent annual written reports to Congress by messenger, as did the next 24 presidents, until Woodrow Wilson revived the speech in 1913.

While oral messages are now more common than not, Calvin Coolidge, Herbert Hoover, Franklin Roosevelt, Harry Truman, Dwight Eisenhower, Richard Nixon and Jimmy Carter all submitted at least one only in writing.

2. The president and his speechwriter write the State of the Union address.

The last time this may have been true was during the Kennedy administration, when Ted Sorensen would have conferred with the president before writing the speech longhand on a yellow legal pad. Usually, though, the process involves legions of people. When I was a speechwriter in the Ford White House, the writer assigned to the speech briefly met with the president, drafted the initial language and worked with a team of researchers to insert the necessary facts. The speech was then "staffed" to appropriate Cabinet officers for their input. Bureaucrats sometimes suggested stylistic changes to parts of the speech not relevant to their areas of expertise, which was terribly annoying.

There was plenty of unsolicited input, too, throughout the process, from beyond the circle of people who had access to drafts of the speech — though during the Ford administration much of it was intercepted by chief of staff Dick Cheney. All White House speechwriters still vie to write the address, because it's so high-profile, but they hate the process.

3. The address is by necessity a lengthy laundry list.

Of course, everyone — from Cabinet members to members of Congress to lobbyists and activists — wants their programs and causes mentioned. And the speech can indeed go on forever trying to cover every last aspect of the president's agenda and to appease every interest group. Especially susceptible was Bill Clinton, who tended to cover 74 issues in 74 minutes.

But it doesn't have to be that way. Ronald Reagan was more disciplined, developing his State of the Union addresses thematically — freedom in the world, revival of the economy through free markets, strength of civil society. If an item didn't fit those themes, it was left out. Reagan also managed to keep his speeches closer to the 40-minute mark.

4. The state of the union is always "strong."

"Strong," "stronger" and "strongest" have been the preferred adjectives of the past five presidents to describe the state of the union. "Strong is a tempting word," Clinton speechwriter David Kusnet explained. "It's simple, declarative. It's alliterative. And it had the added benefit of being accurate." George W. Bush speechwriter Matthew Latimer defended the use of the word, saying: "If presidents before you said that the state of the union is strong, you say that it's strong. … Otherwise someone is going to say, 'Why didn't he say that the country is still strong?' "

But that part of the speech hasn't always been so formulaic. Lyndon Johnson said the union was "free and restless, growing and full of hope." John Kennedy declared that "the state of this old but youthful Union, in the 175th year of its life, is good." Going back further, Coolidge said in 1928: "No Congress of the United States ever assembled, on surveying the state of the Union, has met with a more pleasing prospect than that which appears at the present time."

While it's understandable that the occupant of the White House would try to put the best face on the situation, the State of the Union address hasn't always been so blindly optimistic, either. James Buchanan declared in December 1860, four months before the Civil War began, that "the Union of the States, which is the source of all these blessings, is threatened with destruction." Andrew Johnson said in December 1865, the year of Abraham Lincoln's assassination: "Candor compels me to declare that at this time there is no Union as our fathers understood the term, and as they meant it to be understood by us."

The bleakest assessment in modern times came from Ford, who amid the recession in 1975 admitted: "I must say to you that the state of the Union is not good: Millions of Americans are out of work. Recession and inflation are eroding the money of millions more. Prices are too high, and sales are too slow." It wasn't what his audience wanted to hear, but, as Kusnet would say, it had the benefit of being accurate.

5. The State of the Union is a president's most consequential speech after the inaugural address.

State of the Union addresses are among the most-watched speeches of a presidency, attracting tens of millions of TV viewers. They involve plenty of theatrics between the sergeant at arms' dramatic announcement of the president's arrival and the partisan pep rally that follows. Yet these speeches have remarkably slight impact.

Little of the legislation proposed in them gets passed. Remember Bush's call for privatizing Social Security? Obama's push for gun control after Sandy Hook? Rather than being persuaded by the speech, members of Congress sometimes chafe at passages where the president claims credit for accomplishments that they perceive were really theirs.

State of the Union addresses don't do much to persuade the public, either. According to Gallup, they rarely affect the president's approval rating.

And few of these speeches are memorable for their prose, though there are occasional standout lines: Clinton's "the era of big government is over" and Bush's "axis of evil."

Presidents are far more likely to have meaningful impact — on emotions, beliefs or policy — with speeches addressing a crisis (Reagan after the Challenger explosion, Bush after Sept. 11, 2001, Obama after the Tucson shooting), speeches about taking the country to war or getting out of one, or speeches focused on a single issue.

Craig R. Smith is a communications professor at California State University at Long Beach and is the author of "Confessions of a Presidential Speechwriter." He wrote this article for the Washington Post.