The mural showed a white man, dressed in blue, hanging from a rope tied to a tree branch. Another person was standing nearby, in a red jersey, and holding a Confederate flag.
The painting was intended to depict an athletic team rivalry.
It's unclear how long the paintings have been inside the South Cumberland Elementary School, located 100 miles east of Nashville, but a complaint was first made in December by a concerned janitor of a nearby elementary school.
On Friday, after months of calls and emails to the superintendent and the school board, David Clark, took his concerns public.
"Germany does not display Nazi symbols. This is not heritage, it is racism," he wrote on a Facebook post.
"No action has been planned or taken as of today so I am asking people to call and let them know in a respectful manner, how you feel about these racist symbols being on full public display where children can see them."
Less than 24 hours later, the post had at least 500 comments and more than 200 shares. Later that same day, the Confederate flag was gone and the mural was repainted to scrap the lynching.
"Concerns regarding graphics in our gymnasium have been dealt with by removing the rebel flags painted on the wall, and by modifying the mural on the wall as well," school principal Darrell Threet said in a statement to CNN.
"I guarantee you the black children noticed it, and the white children don't need to see this either," Clark told CNN.
"Removing it didn't seem like a priority... but white supremacy in this country is becoming too organized and too emboldened to ignore something like this in our schools," he said. "I am glad they got to painting, but I am not sure why they ever wanted lynching a part of their school spirit."
But by Saturday the comments below Clark's post had turned vitriolic, and were overwhelmingly in favor of the mural in its original form.
Some Facebook users mocked the proponents of the removal as "unpatriotic" and disrespectful of Southern heritage.
One Crossville resident told CNN affiliate WZTV she had no problem with the mural.
"It's part of our heritage and how they were brought up so I just don't have a problem with flying the rebel flag," Wendy Reed said. "Kid hanging that would bother me, but sometimes I think we just make it bigger than it needs to be."
Confederate symbols have been hotly debated since deadly protests by white supremacists and neo-Nazis in Charlottesville, Virginia, last year.
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