Trump is the only American president who has been indicted twice: in 2019 for abuse of power and obstruction of Congress, and in 2021 for inciting the storming of the Capitol. He was acquitted by the Senate both times.
The sign was put up in 2021 but was removed in connection with the White House pressuring the Smithsonian to dismiss a museum director, which led to a review of the exhibition's content. It has now been replaced by an older sign where only three presidents who "came close to being removed" are mentioned: Johnson, Clinton, and Nixon.
The Smithsonian states that a future version of the exhibition will include all impeachments, but does not specify a date.
Trump has during his second term tried to control cultural institutions. He has cut budgets, signed an order to "clean out inappropriate ideology" and given Vice President JD Vance – who sits on the Smithsonian's board – the task of stopping funding for programs that are considered divisive or violate federal law.