NASCAR: What does the black flag with the white X mean?

One of the rarest flags in NASCAR was shown during the Pocono 400, but what does it mean and why did it get shown to Bubba Wallace?

Everyone knows all about the green, white, yellow and checkered flags in NASCAR. The green and white checkered flag has become a familiar site since stage racing went into effect, and the red flag is an unfortunate fact of life after huge wrecks or when rain hits. But there are other flags that NASCAR uses that are less common, and one of them flew during the Pocono 400 for Bubba Wallace.

The flag in question is a black flag with a white ‘X.’ As you might expect, it looks exactly like the regular black flag except for the unmistakable marking, and it’s actually a follow-up that flies only when teams aren’t obeying that one. The black flag is shown when a driver needs to report to the pits, either because it has been assessed a penalty or due to damage that NASCAR feels needs to be fixed since it’s too dangerous for the car to proceed in its current condition.

If the car and team in question don’t come in when shown the black flag, perhaps because they are arguing a penalty, the black flag with the white X comes out next, which is essentially a final warning to pit immediately, because NASCAR won’t score any more laps if the car remains on the track.