Washington, June 18 : US President Joe Biden has urged Americans to "acknowledge and condemn the history of slavery". Biden, in a proclamation on Juneteenth Day, said, "This Juneteenth, we are freshly reminded that the poisonous ideology of racism has not yet been defeated -- it only hides." The federal holiday came a month after a white male fatally shot 10 African Americans at a grocery store in Buffalo, New York in a racist attack, Xinhua news agency reported. Prosecutors said the shooter's motive "was to prevent Black people from replacing white people and eliminating the white race and to inspire others to commit similar attacks". "As we confront the awful reality of yet another gunman massacring innocent people in the name of hatred, racism, and fear, we must meet this moment with renewed resolve," Biden stated, referring to the Buffalo shooting. "We must stand together against white supremacy and show that bigotry and hate have no safe harbour in America," he added. Last year, Biden signed legislation establishing Juneteenth, short for "June Nineteenth," as a federal holiday. On June 19, 1865 -- over two years after Abraham Lincoln declared all enslaved persons free -- Union Army troops marched to Galveston, Texas, to enforce the Emancipation Proclamation and ensure that all enslaved people be freed. Juneteenth honors the end to slavery in the United States and is considered the longest-running African American holiday. /IANS