The Southern Poverty Law Center's list of hate groups

That's the number of hate groups operating in the US, according to data from the Southern Poverty Law Center. The Alabama-based nonprofit activist group tracks civil rights and hate crimes and defines a hate group as an organization with "beliefs or practices that attack or malign an entire class of people, typically for their immutable characteristics."

"Over the course of a year, we have a team of investigators that scours the internet for racist publications and real world activities to find out which groups exist, which groups are still active and which groups come along," said Ryan Lenz, a senior investigative reporter for the SPLC's Hatewatch project.

Some are classified as neo-Nazi, white nationalists, Ku Kluz Klan and others. The SPLC labels also include anti-LGBT groups, anti-Muslim groups -- and some are black separatists, who don't believe in interracial marriage and want a nation only for black people, according to the group.

Some critics of the SPLC say the group's activism biases how it categorizes certain groups. For example, there are a number of Christian-based advocacy groups listed because the SPLC says the groups have hateful language and policies regarding the LGBT community. Those groups are very critical of the list arguing that they are faith-based and that the list includes them with neo-Nazi, white supremacy and other groups that may advocate violence. They also say the list compromises their safety, citing an attack by a gunman at the Family Research Council five years ago. The gunman had chosen the organization as his target after finding it listed as an anti-gay group on the website of the Southern Poverty Law Center, according to court documents.