Washington, January 20

Donald Trump became the 45th president of United States today, ushering in a new political era that is cheered and feared in equal measure.

The 70-year-old Republican billionaire placed his left hand on a bible used by Abraham Lincoln and recited the 35-word oath spoken since George Washington, and then launched into a much-anticipated inaugural address.

"We, the citizens of America, are now joined in a great national effort to rebuild our country and restore its promise for all of our people," Trump told a crowd of hundreds of thousands massed on the National Mall.

"Together we will determine the course of America, and the world, for many, many years to come," he said.

"From this day forward, it’s going to be only America first."

Trump's inauguration caps the improbable rise to power of the Manhattan real estate mogul, who had never before held elected office, served in the government or the armed forces.

A crowd of hundreds of thousands looked on, including outgoing president Barack Obama and Trump's defeated election opponent Hillary Clinton — who narrowly missed out on becoming America's first female president.

At 70 years of age, Trump is the oldest man ever to begin work in the Oval Office.

He has vowed to tear up Obama's policies and re-examine decades-old alliances with Europe and in Asia.

Beginning today, his team plans a rolling series of daily executive orders to roll back Obama's agenda.

But he enters office with a 37 per cent approval rating, the lowest on record, according to a CBS News poll.

His inauguration was notably more sparsely attended than that of Obama in 2009 and 2013.

Many will look to Trump's inaugural speech for efforts to unify a country divided by politics — and increasingly, by culture.

The most noted inaugural addresses had sought to lift Americans' gaze up from the rancour and troubles of the day towards the horizon and a better tomorrow.

Inaugural addresses — from Lincoln to John F. Kennedy — echo across American history. Phrases like "malice towards none" and "ask not what your country can do for you" have been carved into the vernacular.

Earlier in the day, Trump had traced the steps of many presidents past, attending a prayer service at St. John's Church before heading to the White House, where he was greeted warmly by Obama. "Mr President-elect, how are you?" Obama asked his successor, after having deposited a letter in the Resolute desk and left the Oval Office for the last time.

After his speech, Trump attended a luncheon inside the Capitol, before heading back to the White House to begin the business of governing.

'From now on, it's only America first'

WASHINGTON: President Donald Trump vowed in his inaugural address on Friday that every US decision would be guided by a vision that puts “only America first.” “From this day forward, a new vision will govern our land. From this day forward, it’s going to be only America first,” he said.

“Together we will make America strong again. We will make America wealthy again. We will make America proud again. We will make America safe again. And, yes, together, we will make America great again,” Trump said as he concluded his address. “Thank you. God bless you and God bless America!”

Ten key promises he made for his first day as president

• Introduce a constitutional amendment for congressional term limits
• Freeze hiring for the federal government to reduce payrolls, although the military, public safety and public health agencies would be exempt
• Ban White House and congressional officials from becoming lobbyists for five years after they leave the government
• Announce plans to renegotiate the North American Free Trade Agreement with Canada and Mexico or withdraw from the deal
• Formally withdraw from the Trans-Pacific Partnership
• Lift restrictions on mining coal and drilling for oil and natural gas
• Remove any Obama-era roadblocks to energy projects such as the Keystone XL pipeline
• Cancel US payments to UN climate change programmes and redirect the money to US water and environmental infrastructure
• Stop all federal funding to “sanctuary cities,” places where local officials don’t arrest or detain immigrants living in the country illegally for federal authorities
• Suspend immigration from regions associated with terrorism where vetting is difficult