What states were the KKK common in?

Unfortunately, few states were immune to the Ku Klux Klan during its heyday. The strongest presence of the Klan was in the southern states (including Georgia, Alabama, and Mississippi), where members defended segregation and contributed to the oppression of black people. A number of KKK members even got elected to office, enabling them to pass laws that further restricted minorities. But while the power of the Klan in the south was well-known, newspaper articles from the early 1920s show that there were Klan meetings in a number of mid-western states, and even on the east coast: Massachusetts and Maine both had chapters. There was also a huge march in support of the Klan in Washington DC in 1925.

The Klan was especially active during times when there were large numbers of immigrants coming to the United States, as well as during times of social change: for example, the "Roaring Twenties" saw a resurgence of Klan influence. Although this decade was a period of prosperity and new social freedoms, the Klan represented a backlash against these changing standards. Members opposed greater political rights for women, and were vocal in protesting increased educational opportunities for minorities. In fact, in the late 1920s, the Klan had their own radio station: WTFF broadcast in the Washington DC area.

Ultimately, the Klan returned to being a mainly southern organization (with some power in such middle-Atlantic states as Virginia and Maryland). But if you looked on a map in the 1910s and 1920s, you would have seen the presence of the Klan in a surprising number of states.