On the occasion of Juneteenth, a day that commemorates the end of slavery, President Trump took a moment to complain that the national holiday even exists.

“Too many non-working holidays in America,” Mr. Trump wrote on social media, just hours after his press secretary, Karoline Leavitt, made a point of noting that White House staff had shown up to work.

The president’s decision to snub Juneteenth — a day that has been cherished by generations of Black Americans before it was named a federal holiday in 2021 — is part of a pattern of words and actions by Mr. Trump that minimize, ignore or even erase some of the experiences and history of Black people in the United States. Since taking office in January, he has tried to reframe the country’s past involving racism and discrimination by de-emphasizing that history or at times denying that it happened.

Government websites have been scrubbed of hundreds of words, including “injustice” and “oppression.” Federal agencies eliminated or obscured the contributions of Black heroes, from the Tuskegee Airmen who fought in the military, to Harriet Tubman, who guided enslaved people along the Underground Railroad. School libraries were purged of writings by pre-eminent Black authors like Maya Angelou. Mr. Trump has assailed the Smithsonian Institution for what he characterized as “divisive, race-centered ideology” in its exhibits on race. He ordered the renaming of monuments to honor Confederate soldiers who fought to preserve slavery.

And on Thursday, instead of marking the day when the last enslaved people were informed of their freedom from forced labor, Mr. Trump lamented that Americans had a day off from work and suggested that the holiday was little more than a drain on the economy.