The U.S. population is about 300,000,000. Whites represent about 80%, or roughly 240,000,000. If you check the numbers of executions in the U.S., you’ll see that there were about 1,000 in the period from 1977 to 2005. 584 of those executions were of whites. That’s about 20 executions per year on average, meaning that whites have a chance of 1 in 12,000,000 of being executed.
There are about 40,000,000 African Americans, representing roughly 13 % of the U.S. population. 339 executions in the 1977-2005 period were of African Americans. That’s about 12 a year, meaning that blacks have a chance of 1 in 3,300,000 of being executed.
A black person in the U.S. is therefore almost 4 times more likely to be executed. Even if we assume that this higher probability of being executed correctly reflects a higher probability of being involved in crime that comes with capital punishment – and that’s something we shouldn’t assume, because it’s likely that there are injustices involved, e.g. inadequate legal representation and such – that shouldn’t put our minds at ease. We then still have to ask the question: why are blacks more likely to be involved in capital offences? Surely not because of their race. Something happens in society that leads to this outcome, and it’s likely that there are injustices involved: for example, inadequate education, poverty levels, discrimination etc.