Free tickets to outgoing US President Barack Obama's farewell speech in Chicago were allocated within half an hour as thousands queued early on Saturday morning.

Thousands lined up for a chance to get a ticket for Tuesday's speech at McCormick Place from 4.30am, NBC News Chicago reported.

Officials had initially said that people were not allowed to queue until 6am but shortly afterwards 7,000 people had gathered and anyone not in line by 6.30am was told they would not get a ticket.

Tickets were handed out from 8am on a first-come-first-served basis with just one given per person.

Kenita Christmas, who was first in line to get her ticket with her daughter, had queued from 4.30am.

"This feels amazing. First in line!" she said.

"It's monumental, and to have my daughter here with me - it's going to be amazing."

Obama said in a statement on Monday that he plans to highlight in his speech how the American people have helped him lead during his presidency.

"I'm thinking about [my remarks] as a chance to say thank you for this amazing journey, to celebrate the ways you've changed this country for the better these past eight years, and to offer some thought on where we all go from here," he wrote.

"Since 2009, we've faced our fair share of challenges, and come through them stronger. That's because we have never let go of a belief that has guided us ever since our founding - our conviction that, together, we can change this country for the better."

The US President's farewell address is a tradition that dates back to 1796 when George Washington said goodbye to Americans before transferring power to his successor, John Adams.