The president left Delaware earlier in the day after testing negative for COVID-19.
Biden didn't stop to answer reporters' questions while boarding Air Force One, in what was his first public appearance since dropping out of the presidential race.
Biden was diagnosed with COVID-19 last week and had been recovering in Rehoboth Beach.
That is also where he ultimately made the decision to drop out of the 2024 presidential race.
Biden is set to address the nation on Wednesday night about his vision for the final few months of his term.
"Tomorrow evening at 8 PM ET, I will address the nation from the Oval Office on what lies ahead, and how I will finish the job for the American people," he said in a statement on X.
Meanwhile, Vice President Kamala Harris was on the campaign trail Tuesday, holding the first rally of her 2024 presidential campaign in Milwaukee, Wisconsin.
"I am told, as of this morning, we have earned the support of enough delegates to secure the Democratic nomination," Harris said.
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The Republican nominee, former President Trump, is preparing for a rally in Charlotte, North Carolina on Wednesday.
He posted a series of comments about Harris and Biden on Truth social on Tuesday.
"Lyin' Kamala Harris destroys everything she touches!" he wrote. "Does Lyin' Kamala Harris think Joe Biden is fit to run the U.S.A. for the next six months? She must answer the question."
Trump's pick for VP, Senator JD Vance, is also asking that question.
"Can anybody just admit that if Joe Biden is not fit to run for president, he ain't fit to serve as president of the United States either?" Vance said.
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White House Press Secretary Karine Jean-Pierre called that claim "ridiculous" during an appearance on The View.
"What I will say is the president decided to not run for re-election. That's it. That's all he decided on. He wants to continue to do the work," she said.
Late Monday afternoon, we heard from Biden for the first time since he made that announcement. He called in to campaign headquarters in Wilmington, Delaware, where Vice President Kamala Harris was making an appearance.
"I want you to know, I won't be on the ticket but I'm still going to be fully, fully engaged," Biden said on the call. "I've got six months left of my presidency. I'm determined to get as much done as I possibly can both foreign policy and domestic policy."