Barack Obama has waved goodbye to supporters in Washington DC, after handing over power to newly-inaugurated US President Donald Trump.

Mr Obama and his family were escorted by President Trump and Vice President Mike Pence to the east steps of Capitol Hill, where they departed US Congress in a helicopter.

Former vice president Joe Biden and his family, who were also escorted by Mr Trump and Mr Pence, were taken away in a motorcade.

After arriving at Fort Andrews military base, Mr Obama and his family will be taken to Palm Springs, California.

Earlier, Mr Obama left a personal note for his successor in the Oval Office - a customary gesture for an outgoing president.

In his own departing letter in 2009, George W Bush told Mr Obama: "You have just begun a fantastic chapter in your life".

Hours before that chapter ended, Mr Obama posted a message on Twitter saying it had been "the honour of my life to serve you".

He added: "You made me a better leader and a better man. I won't stop; I'll be right there with you as a citizen, inspired by your voices of truth and justice, good humour, and love."

Referencing the wave of optimism that preceded his first term as president, he added: "I'm still asking you to believe - not in my ability to bring about change, but in yours.

"I believe in change because I believe in you."

It's been the honor of my life to serve you. You made me a better leader and a better man.

— President Obama (@POTUS44) January 20, 2017

I won't stop; I'll be right there with you as a citizen, inspired by your voices of truth and justice, good humor, and love.

— President Obama (@POTUS44) January 20, 2017

I'm still asking you to believe - not in my ability to bring about change, but in yours. I believe in change because I believe in you.

— President Obama (@POTUS44) January 20, 2017

As they said goodbye to members of the White House residence staff, Mr Obama and his wife Michelle were presented with two US flags that were flown atop of the building.

One of the flags was raised on the first day of Mr Obama's presidency, while the other was flown on his final morning in charge.

Mr Obama's Twitter handle has also been changed - with him becoming @POTUS44, as Donald Trump takes over the @POTUS account.