It's legal, since it's covered by freedom of speech laws.Of course, I do not support the KKK, but however it is legal in USA. Today, many sources classify the Klan as a "subversive or terrorist organization" In 1882, the Supreme Court ruled in "United states V. Harries" that the Klan Act was partially unconstitutional. read more
The Ku Klux Klan is just a blanket term to refer to various groups that peddle views that can be generally characterized as racist/anti-Semitic. To answer your question, the KKK is a legally allowed entity today. read more
The Ku Klux Klan, with its long history of violence, is the most infamous — and oldest — of American hate groups. Although black Americans have typically been the Klan's primary target, it also has attacked Jews, immigrants, gays and lesbians and, until recently, Catholics. read more