The message #IStandWithBubba was painted on the infield grass at the Superspeedway.
"Late this afternoon, NASCAR was made aware that a noose was found in the garage stall of the 43 team", NASCAR said in a late Sunday statement.
At 3:05, the entire NASCAR garage, including all 40 drivers and team crew members, pushed Wallace's auto to the front of the grid, the Charlotte Observer reported. Wallace wore a "I can't breathe" Black Lives Matter t-shirt at the Martinsville NASCAR Cup race, and was quick to throw his support behind the movement.
The incident occurred just days after Wallace, NASCAR's only black driver, successfully petitioned officials to ban the Confederate flag from all events and venues. "As we have stated unequivocally, there is no place for racism in NASCAR and this act only strengthens our resolve to make the sport open and welcoming to all".
While some in the South see the flag as a source of pride and a remembrance of its soldiers who died in the Civil War, many Americans see it as a symbol of oppression and of a dark chapter in American history. "The display of the confederate flag will be prohibited from all NASCAR events and properties".
That didn't stop a plane flying the controversial flag over the Talladega Superspeedway in Lincoln, Alabama on the weekend.
The 26-year-old driver is a member of the Richard Petty Motorsports team.
NASCAR was among the top-three trending topics on Twitter in the US on Monday, with supporters of Wallace using the hashtag #IStandWithBubba. Fans protested the decision in Talladega for Sunday's race.