To mark the holiday celebrating the legacy of Martin Luther King Jr., Vice President-elect Kamala Harris participated in a service activity focused on food insecurity in the nation's capital on Monday. 

She packed bags of food alongside her husband Doug Emhoff at Martha's Table, an initiative focused on increasing access to healthy meals in Southeast Washington.

"I think it's so important to remember that Dr. King was killed in large part, I believe, because he was on the verge of bringing together the Civil Rights movement around racial justice with the fight for economic justice," Harris said. "And when we look at where we are as a country today, when we look at recent events, we know that the fight that Dr. King was engaged in is still a fight in America, which is to recognize the connection and to recognize our collective responsibility to address these injustices."

She also spoke about the tasks ahead as she prepares to become vice president, saying she and Biden are going into Wednesday "ready to do the work." 

"And we've got a lot of work to do," she added, referencing plans for vaccinations and economic recovery. 

When asked if their proposed one-time $1,400 stimulus check was enough for Americans, Harris called it a "start." 

"There's a lot more to do, which is why there are so many other components to our relief package and the work that we are committed to doing going forward," she said. 

Finally, Harris spoke about how she's feeling ahead of her historic swearing-in, which has faced unprecedented security threats. 

"I am very much looking forward to be sworn in as the next vice president of the United States, and I will walk there, to that moment, proudly with my head up and my shoulders back," Harris said.

-ABC News' Averi Harper

Country singer Garth Brooks will be joining the Biden inauguration celebration on Wednesday and perform during Biden's swearing-in ceremony at the Capitol, the Presidential Inaugural Committee announced Monday.

Brooks has performed for every president since Jimmy Carter, with the exception of Ronald Reagan.

He will join previously announced performers Lady Gaga and Jennifer Lopez. During the virtual press conference, Brooks stressed that his decision to perform at the Capitol was not a political one, but one focused on unity -- a message that the Biden administration has pushed as they get ready to enter office. 

"I am a civilian of the greatest country on the planet," Brooks said. "So our job is to work as hard as we can for all of us to have a better future than before." 

Brooks even quipped that he "might be the only Republican" at the inauguration, but said he wanted to move past the divided nature of the country.  

-ABC News' Molly Nagle

Alex Padilla officially resigned as California's secretary of state on Monday in order to assume Vice President-elect Kamala Harris' Senate seat. 

Harris resigned her Senate seat earlier Monday.

Padilla called it a "true honor and privilege" to serve as California's secretary of state in a statement reflecting on the agency's progress over the past six years. 

"As I prepare to enter the United States Senate, I will carry on the mission of building a more inclusive democracy and economy for all," Padilla added. 

James Schwab, the former chief deputy secretary of state in California, will serve as interim secretary of state.

-ABC News' Kendall Karson

More than 21,500 National Guardsmen are currently in Washington, the D.C. Guard confirmed to ABC News on Monday.

The security preparations come ahead of Biden’s inauguration and in the aftermath of the deadly Capitol raid conducted by Trump supporters earlier this month. 

The ramp-up in the number of guardsmen in the nation's capital means there could be four times as many American military service members in the city than there are in Iraq and Afghanistan combined.

The guardsmen are working in shifts to provide round-the-clock security both inside the Capitol and around the perimeter of the Capitol grounds. 

-ABC News’ Luis Martinez

The White House has released a pre-taped farewell address from President Trump on his final full day in office.

"We did what we came here to do – and so much more," Trump said, speaking from scripted remarks directly into the camera and standing behind a lectern with the presidential seal. "This week, we inaugurate a new administration and pray for its success in keeping America safe and prosperous. We extend our best wishes, and we also want them to have luck -- a very important word."

Trump thanked several people, including Vice President Mike Pence.

"Most of all, I want to thank the American people," Trump said. "To serve as your president has been an honor beyond description. Thank you for this extraordinary privilege."

Trump then condemned the riot at the Capitol and called on Americans to "unite around our shared values."

"All Americans were horrified by the assault on our Capitol. Political violence is an attack on everything we cherish as Americans. It can never be tolerated," Trump said.

He warned that the greatest danger the country faces as he leaves office is "a loss of confidence in our national greatness" -- going on to talk about the shared "heritage" of the country under threat and condemning "political censorship and blacklisting."

"Now, as I prepare to hand power over to a new administration at noon on Wednesday, I want you to know that the movement we started is only just beginning," he said, closing out the 20-minute farewell address.