WASHINGTON - United States President Donald Trump marked his 100th day in office on Saturday (April 29) with a return to his power base in a rousing campaign style rally at the New Holland Arena in Harrisburg, Pennsylvania - a state hurt by manufacturing job losses which swung his way last year after not having voted for a Republican since 1988.

"Whether we are black or brown or white we all bleed the same red blood of patriots, and we all share the same glorious freedoms of our magnificent country" he said. "We are all made by the same almighty God, as long as we remember this we will.. never fail."

"For the last 100 days my administration has been delivering every single day...whether putting our coal miners back to work, protecting America's steel and aluminium workers... we are keeping one promise after another" he told the capacity crowd of around 10,000 many of whom had been queuing since the afternoon.

He said his measures had created over 600,000 new jobs, and under his administration there had been a 73 per cent reduction in illegal immigration across the US's southern border.

He touted the appointment of conservative Supreme Court judge Neil Gorsuch, the withdrawal from the "horrible (and) disastrous" Trans Pacific Partnership, and pledged to renegotiate the North Atlantic Free Trade Agreement (NAFTA) which groups the US, Canada and Mexico), saying "if we don't get a good deal and a fair deal we will either renegotiate or terminate it."

Signalling that he may withdraw from the Paris Climate Accord, he said full compliance with the "one sided agreement" could "ultimately shrink American GDP by 2.5 trillion dollars over a 10 year period."

"I'll be making a big decision over the Paris Accord over the next two weeks," he promised.

He emphasised coming tax cuts, pledged to repeal the Affordable Care Act, insisted his promised wall on the Mexico border would be built, and pledged that he would take the fight against crime to "sanctuary cities" to crack down on illegal immigrants and gangs.

On the foreign front, he underscored plans to beef up the military, and praised China's President Xi Jinping saying China was "really trying" to help with the North Korea crisis. The Islamic State in Iraq and Syria (ISIS) was on the run and the US would smash it, he said.

Hours before, culminating a flurry of executive orders, he signed two directing a review of NAFTA and other free trade agreements, and creating a permanent trade policy office at the White House headed by Peter Navarro, his main advisor on trade who blames China for leaching away American manufacturing jobs.

This raised the number of President Trump's executive orders to 32 in his first 100 days, more than any newly installed President since Franklin D. Roosevelt.

But many of the orders do not initiate immediate action, instead ordering studies and commissions to investigate issues and make recommendations weeks or months down the road. The review of free trade agreements for instance gives the Secretary of Commerce 180 days to conduct a comprehensive review of whether free trade agreements have brought the benefits expected from them.

Top aide Kellyanne Conway writing on Saturday in USA cited April figures to noted that the number of people collecting unemployment benefits has hit a 17-year low. Mr Trump had started to chip away at a burdensome regulatory framework that stifled entrepreneurship and innovation, and abroad the President had shown strength and resolve by military action in Syria and Afghanistan, she wrote.

She added: "These facts fly in the face of a presumptively negative portrayal by many in the media."

In fact the President's overall popularity rating is the lowest of any President in modern American history. However, among his supporters, it still runs over 90 per cent.

"To some extent his rhetoric and his largely symbolic executive orders have played rather well in some quarters," Cornell University professor Glenn Altschuler told The Straits Times.

"Support among those who voted for him remains much as it has been. And Wall Street has reacted very, very favourably to his executive order that for every regulation added two must be eliminated - and to his proposals to dramatically reduce corporate taxes."

"Here again, however, he will have to deliver - and with both deregulation and especially with tax reform that will not be easy."

The day offered a glimpse into the country's divisions as well.

As the President worked the cheering crowd in Harrisburg, big media names gathered in Washington DC for the annual White House Correspondents' Association dinner, a black tie affair traditionally attended by the President - but not this time.

Instead, in Harrisburg Mr Trump opened his rally with a broadside against the media.

"There's another big gathering taking place tonight in Washington DC," he said. "A large group of Hollywood actors and Washington media are consoling each other in a hotel ballroom in our nation's capital right now."

"I could not possibly be more thrilled than to be more than 100 miles from the Washington swamp spending my evening with all of you," he said.

Earlier in the afternoon, tens of thousands gathered in Washington DC, surrounding the White House, in a Climate March essentially protesting President Trump's series of actions rolling back environmental safeguards.

These include appointing a well-known climate change sceptic and fossil fuel industry fan Scott Pruitt as head of the Environmental Protection Agency (EPA); opening up the Arctic to oil exploration - reversing a late Barack Obama era order; and signalling intent to hand back millions of acres of federally protected land to state control, potentially leaving vast tracts open to commercial exploitation.