White supremacy is both an ideology and a system. As an ideology, it holds that white people are superior and should dominate. As a system, it describes how laws and institutions in the US were built to give white people power and resources, from slavery and Native land seizures to Jim Crow, immigration bans and redlining. Scholars use the term for the system even when no individual intends harm.
Organized white supremacist groups have used terror throughout US history. The Ku Klux Klan formed in Pulaski, Tennessee, in 1865 to attack Black political power during Reconstruction. A second Klan in the 1920s claimed millions of members. White supremacist violence also included lynching and massacres such as Tulsa in 1921.
The threat continues. In October 2020, the Department of Homeland Security called white supremacist extremists the most persistent and lethal threat in the homeland. Recent attacks include the 2015 Charleston church shooting, the 2019 El Paso Walmart shooting targeting Latinos and the 2022 Buffalo supermarket shooting targeting Black shoppers.