In recent weeks, homeowners in Virginia, Texas, Colorado and Washington state have hung empty chairs from trees. This comes in the wake of actor Clint Eastwood’s empty chair speech at the Republican National Convention. Never mind agreeing or disagreeing with the presidential candidates. Eastwood clearly intended the viewer to imagine President Barack Obama in that empty chair. And those who displayed chairs in their yards, beginning less than three weeks later, clearly intended them to represent hanging Obama.

Some claimed they tied chairs in trees to prevent theft. That doesn’t pass the laugh test when other chairs remain on the homeowners’ porches. Neither do claims that the displays aren’t references to lynching. The implied hanging-in-effigy of our first African-American president is about more than politics. If the chair hangers didn’t understand the shameful history they were invoking, they should have. Lynching is not a joke.

Recently I participated in “Without Sanctuary,” a conference at the University of North Carolina, Charlotte, on the topic of lynching, which was the focus of my master’s degree history research at the University of Maine 10 years ago. The conference took its name from a traveling exhibit and book of photographs that chronicle the horror of this American terrorism, which hardly was confined to Southern states. (The only reported lynching in Maine happened in Mapleton in 1878.) The “Without Sanctuary” exhibit is at the Levine Museum of the New South until the end of the year, then goes to its permanent home at the National Center for Civil and Human Rights in Atlanta.

For three days, scholars, educators and descendants of both the lynched and the lynchers discussed what we wished hadn’t happened. But it had. We all wished lynching didn’t have present-day repercussions. But it does. The barbaric practice reached its peak around the turn of the 20th century, as tallied by the National Association for the Advancement of Colored People and Tuskegee Institute (now Tuskegee University). The reported number of Americans — young, old, male, female, of varied racial and ethnic backgrounds — whose lives were taken in atrociously brutal ways ranged between 3,500 and 5,000 from the 1880s through the 1960s. But scholars agree that the unreported numbers may have been as high as 15,000 between the Civil War and the Civil Rights movement. Even the lowest of the totals is more than the number who died on 9/11. Yet federal anti-lynching legislation never made it past Southern senators bent on preserving their supposed right to enforce white supremacy with impunity.

The overwhelming majority of lynched individuals were black males, killed because a white person somehow became offended, and white community members demanded blood. Most commonly committed by rope, though in myriad other ways as well, a lynching was designed to scare African Americans into submission. Lynchers often left their victims hanging on the edges of black neighborhoods, so every resident would understand the unmistakable message of white supremacy. Like the burning crosses of the Ku Klux Klan, lynchings were warnings to African-Americans who, in local white opinion, didn’t know or keep “their place.”

Some white Americans still think black Americans need to keep to the “place” whites have picked out for them or, worse yet, should not be Americans at all. The fringe birther movement that disputes the president’s Hawaii birth certificate is one national example. Late-September comments by Lewiston Mayor Robert Macdonald, directed against his city’s Somali population, are a local one. An Arkansas legislator recently said, among other things, that slavery was a “blessing in disguise” for the Africans stolen from their homes. From New York to San Diego, nooses have been hung on office doors of employees of color, and white teens have been reprimanded or expelled from schools for wearing Klan garb and tying ropes around the necks of black fellow students.

Lynchings and racist threats didn’t end in some distant past: Matthew Shepard and James Byrd Jr. both were killed in 1998. We can’t ignore this history, or joke about it.

Disagreements about policy and politics are one thing. Threats of racially motivated, violent hate crimes are quite another and have no place in a democracy that claims to celebrate diversity and equal rights.

Stephanie Harp, of Bangor, is a writer and independent scholar. She welcomes comments at her blog,