The hangman's noose has come to be one of the most powerful visual symbols directed against African-Americans, comparable in the emotions that it evokes to that of the swastika for Jews. Its origins are connected to the history of lynching in America, particularly in the South after the Civil War, when violence or threat of violence replaced slavery as one of the main forms of social control that whites used on African-Americans. The noose quickly became associated with the Ku Klux Klan.
In the early twentieth century, when the rise of the Second Ku Klux Klan coincided with the height of lynching incidents (most of the victims of which were African-American), the noose became cemented as a key hate symbol targeting African-Americans. The noose may appear as a drawing or rendering, but also quite common is the use of actual nooses to intimidate or harass African-Americans (or sometimes other minorities) - for example, by leaving one at someone's home or at their workplace.