Obama writes thank you letter for his countrymen

"Throughout these eight years, you have been the source of goodness, resilience, and hope from which I've pulled strength. I've seen neighbours and communities take care of each other during the worst economic crisis of our lifetimes. I have mourned with grieving families searching for answers - and found grace in a Charleston church," Obama said.

Before he leaves the White House one final time Friday morning to attend the swearing-in ceremony of his successor Trump at the Capitol Hill overlooking the majestic National Mall, Obama will leave a parting letter for the 45th President of the US.

"But before I leave my note for our 45th president, I wanted to say one final thank you for the honour of serving as your 44th. Because all that I've learned in my time in office, I've learned from you. You made me a better President, and you made me a better man," Obama said in his letter to his countrymen.

"I've taken heart from the hope of young graduates and our newest military officers. I've seen our scientists help a paralysed man regain his sense of touch, and wounded warriors once given up for dead walk again," he said.

"I've seen the youngest of children remind us through their actions and through their generosity of our obligations to care for refugees, or work for peace, and, above all, to look out for each other," said the outgoing US President.

Obama said he has seen the American people, in all their decency, determination, good humour, and kindness.

"And in your daily acts of citizenship, I've seen our future unfolding," he said.

"All of us, regardless of party, should throw ourselves into that work - the joyous work of citizenship. Not just when there's an election, not just when our own narrow interest is at stake, but over the full span of a lifetime. I'll be right there with you every step of the way," Obama wrote.

"And when the arc of progress seems slow, remember: America is not the project of any one person. The single most powerful word in our democracy is the word 'We.' 'We the People.' 'We shall overcome.' Yes, we can," said the 44th American President in his final letter to his countrymen.