Why is this the case

Many reasons, but here are a few. A higher percentage do not have a strong father figure at home. I believe all children from fatherless homes have a higher rate of incarceration.

A higher percentage live in poor city and urban areas. Because of the higher crime rate, in those areas coupled with lack of strong father figure, it leads to young black youth looking towards local gangs leaders, and drug dealers as examples of success.

Another couple of reasons is what happens once arrested. A higher percentage of black have less connections with people of influence once arrested than white people do. A higher percentage have less financial ability to hire the top attorneys, once arrested, than whites do.

Also in many areas racial profiling still goes on.

 

two more reasons. White dope sellers don't stand on street corners in doper areas looking like white dope sellers. The police seldom pass up easy arrests.

Second, Congress has put ten times or so the penalty on possessing black people's favorite drugs that is on rich white people's (congress peoples?) favorite drugs.

>Also in many areas racial profiling still goes on

Not west of the Rockies and north of San Francisco. Don't know about the rest of the country.