As nasty as Donald Trump gets, his poll numbers stay strong. Why are so many of his followers so mean-spirited? 

An image will help us understand. It’s a photograph of 15-year-old Elizabeth Eckford, walking down the street in 1957 as she tries to become one of the first black students at Little Rock Central High School. She is surrounded by a crowd of white people as one female student snarls hatefully behind her.

Here is the iconography of a tragic, traditionally American call and response. The call: a challenge to the status quo of white-people-on-top; the response: outbreaks of meanness, many merely vile, embracing rhetorical weapons, many murderous, taking up physical weapons. The bloody history of lynching, with its festive mobs and souvenir post cards and body parts, bristles with personal provocations to the racial status quo.

In the 19th-century, the Ku Klux Klan arose in the South as a response to black citizenship. Federal action put it down, but in the 1920s, a resurgent Klan added immigrants, Catholics and unruly women to its black targets. In the West, official massacres and the "Driving Out" of the late 1800s had already ethnically cleansed Native Americans and run off Chinese workers and business people. 

After President Harry Truman embraced civil rights, Southern Democrats formed their own segregationist States’ Rights (“Dixiecrat”) party in 1948. After the Supreme Court ordered an end to school segregation in Brown v. Board of Education came “massive resistance” and the murder of 14-year-old Emmett Till. As the civil rights movement gained strength, four girls were murdered in the 1963 bombing of the Sixteenth-Street Baptist Church in Birmingham, Ala. 

Today’s challenge to white people on top is the most acute in history: the election and re-election of a president who is black, with a wife who is black and two daughters who are black. Responses to this challenge began early, with the vow to make Obama a one-term president, and they continue in congressional refusal to govern, birtherism, “You lie!” and countless visual stereotypes that lost currency a century ago. In addition to simply being black, the president has embraced immigration reform, a reform identified with brown people. 

Without Barack Obama, there is no Donald Trump....