“I didn’t think there was much new,” Mr. Prokop said. “This didn’t reach out to anybody other than the people he already connected with.”
A glass case in the exhibit holds scores of campaign buttons from Mr. Obama’s presidential races on its left side and magazine covers on the right — five from Time magazine alone — featuring the president and the first lady, Michelle Obama, through the years.
In the center, the dress Mrs. Obama wore at the event marking the 50th anniversary of the March on Washington was placed prominently, along with a signed copy of Mr. Obama’s speech marking the occasion.
Some visitors on this typically busy Saturday, like students on field trips, whizzed by the display. Other attendees stopped, stared and reflected, some stroking their chins, some shaking their heads. One woman was visibly emotional. She declined to be interviewed because she was “having trouble processing.”
Another visitor, Sonia Gonzalez, 31, had traveled from Brooklyn to participate in the Women’s March. “I think it’s just really something that you can look at and say that we’ve come a long way,” she said. Her mother, Gretchen Nearon Gonzalez, viewed the entire exhibition as an expression of her own struggles as an African-American. Taking part in the march was a symbolic passing of the torch to her daughter.
“Thank you for the fire,” said the elder Ms. Gonzalez, 62, as a message to Mr. Trump.
Others were less complimentary toward the former president.
“I didn’t agree with what Obama stood for,” said Phillip Stange, a 38-year-old Trump supporter who drove six hours from Virginia to attend his inauguration. “So I’m glad he’s out of office.”
A few blocks away, at the National Portrait Gallery, a photograph of Mr. Trump from 1989 greeted viewers near an entrance doorway, situated next to prints of the actress Halle Berry and the children’s show host Fred Rogers. A security guard kept watch for vandals.
The picture, taken by Michael O’Brien, was used as a Fortune magazine cover and then again for Mr. Trump’s second book, “Trump: Surviving at the Top.” It shows Mr. Trump throwing an apple in the air with his right hand and resting his left on his hip.
Curious passers-by, ranging from those wearing pro-Trump memorabilia to participants in the Women’s March, stopped by the portrait. Most silently observed for about a minute, like clockwork, and then squinted to read the caption, which described Mr. Trump’s “stunning rise to the presidency by defeating Hillary Rodham Clinton after one of the most volatile and divisive campaigns in recent memory.” With that, and perhaps some more reflection, they walked to the next exhibit. Some took pictures with the photograph. Many marveled at how young Mr. Trump looked.
Beth Piecora, who traveled from Lutz, Fla., for the inauguration, said the “confidence he exudes” in the photograph was what stood out. She was wearing a camouflage Make America Great Again cap and browsed the gallery with her 29-year-old son.
“He doesn’t let things get to him,” Ms. Piecora said of Mr. Trump, whom she supported during the primaries. “He just grabs life with gusto with the apple in the air.”
At the African-American museum, the placement of the display honoring Mr. Obama was intended to express the end of a journey. Mr. Trump’s photograph is installed near the National Portrait Gallery’s entrance, a beginning of sorts, one floor below a room that holds a portrait of every single president, save Mr. Obama, whose will be there soon.
The gallery is said to be the only building with a complete collection of presidential portraits outside of the White House. Mr. Trump’s portrait will share a room with George Washington’s and Abraham Lincoln’s someday. But for now, as his presidency begins, he has skeptics to win over, including David Whettstone, 58, who works for WPFW, a Washington public radio station.
Mr. Whettstone said he saw the photograph of Mr. Trump as “cleanly businesslike, as opposed to political.” He also said it was a reminder that Mr. Trump could evolve, even if he hasn’t yet, from the caustic presidential candidate who, in Mr. Whettstone’s view, is unable to unify Americans.
“The apple in the air, to me, always represents innovation and ideas,” Mr. Whettstone said. “And so maybe at that time he was more open to innovation and ideas, but I don’t see that theme for now.”