A self-styled anonymous hacktivist released a list of alleged Ku Klux Klan members Monday that included several prominent senators and mayors. While the elected officials denied being members of the hate group, Southern history shows the KKK is no stranger to elected office.

Members of the organization helped elect 12 governors and several Congressmen in the 1920s alone, the Southern Poverty Law Center, a civil rights group, found. KKK members also held office in cities across the nation, including in Texas.

The KKK, an anti-black hate group, was started by ex-Confederate soldiers after the U.S. Civil War in the 1860s. The group, which existed throughout the late 19th century and into the early 20th century, saw a resurgence in the early 1920s, caused in part by an influx of immigrants in the early 1900s. The Klan shifted its message to target not only African-Americans but Catholics, Jews and foreigners of all kinds, gaining membership across the country.

During the group's renaissance in the 1920s, as many as 4 to 5 million people in the U.S. were members of the Klan. In Texas, the grip of the KKK was particularly strong, according to a 2010 retrospective in the Dallas Morning News. Dallas celebrated a "Ku Klux Klan Day," complete with a parade for members at its county fair in October 1923 when 13,000 of its 160,000 residents were Klan members.

"[Candidates] backed by the Kluxers had won control of City Hall and the county courthouse. The city police commissioner and the county sheriff were Klansmen," wrote Bryan Woolley for the Dallas Morning News.

At least 784 hate groups are currently operating in the country, according to the Southern Poverty Law Center, with a high concentration of the Klan operating out of the southeastern United States.

All of the government officials alleged to be in the Klan in 2015 have vehemently denied membership, including several prominent mayors of Southern cities. "I have no idea where this information came from, but wherever it came from, it is wrong," Jim Gray, mayor of Lexington, Kentucky, said Monday.