The White House had hinted it would be a speech that took a softer, bipartisan approach. But the olive branch dangled in the first few minutes of President Donald Trump's inaugural State of the Union address quickly disappeared during the 80-minute exhortation.

Even Trump's fan base, who praised the address for its tough but optimistic and controlled tone, didn't find much of the unity they were promised.

"He was going tonight to come right into this and offer some healing and some positive reinforcement. I think he gave Democrats every reason to sit on their hands and walk out early," Fox News host Juan Williams said. "He took credit for everything. To me, it was bellicose and ... I'm sitting here a little struck."

The third longest State of the Union speech began with a call for politicians to set aside their differences and "deliver for the people".

"This in fact is our new American moment, there has never been a better time to start living the American dream," Trump said, spruiking his large tax cuts and booming economy before segueing from gang violence and drugs into a four-point plan for stricter immigration laws and a border wall.

He began by calling for unity but "delivered a speech filled with hateful rhetoric demonising immigrants and gave [us] nothing to suggest he wants to move us from the dangerous course he has set," said Democrat Senator Tom Udall.

The real question is whether the 5159-word address, which traversed a mammoth range of topics from support for paid parental leave to destroying North Korea, will lead to actual action.

Alison Hanson, a political scientist at California's Dominican University, has spent a decade studying State of the Union addresses and the way presidents use them to set policy priorities by including specific calls for Congressional action.

Historically, the median number of requests for action is 31; about 43 per cent of which ended up being at least partially fulfilled.

Trump had far fewer than the average number of requests and those he did make were vague, she told Fairfax Media.

He called for Congress to restrict aid to countries that didn't support the decision to move the US embassy in Israel to Jerusalem. He called for the price of prescription drugs to be reduced and for $1.5 trillion to be allocated for new infrastructure. And, in a detail-devoid call he has been making since 2016, he asked for the opioid epidemic to be addressed.

"He did not see this speech as something to set him up for the next two years, as something to lay out plans and well-developed goals," said Ms Hanson, co-author of Addressing the State of the Union. "But the administration really hasn't acted that way since they took office. They don't have a well-fleshed out legislative agenda and if you don't have an agenda it's really hard to come up with actual policy requests."

As the USA Today's veteran Washington reporter Susan Page wrote, the most remarkable thing about the speech was that it was completely unremarkable. Trump stayed on script rather than indulging his penchant for inserting unplanned insults, hyperboles and mystifying non-sequiturs.

Admirers and critics alike said it was not nasty, vindictive or out-of-control. But it was under-handedly divisive, wildly exaggerated in some parts and far from a concrete blueprint for uncertain times.

Trump may be one of the most extraordinary presidents in history but will his inaugural State of the Union have a similar legacy?

"Whatever he said on Twitter that morning matters more," said Jennifer Grossman, a speechwriter for George H. W. Bush. "And his base doesn't care what's in the State of The Union, they'll care what he tells them was in the State of The Union.

"Speeches now, with the news cycle, are like the morning dew, they'll just evaporate in terms of significance."