1) child porn

2) terrorism

3) money laundering

3) war on [edit: some] drugs

It was specifically "war on some drugs". Americans love drugs, and we even love dangerous or mind altering drugs. But some drugs, for various socioeconomic reasons, we have declared evil.

more specifically, to keep black people from voting

Sure, for marijuana. But not all substances are the same. If you've ever gone through the hell of having a family member or close friend being addicted to heroin or coke or other physically-addictive "hard" drugs, you'll see that they're not in the same risk category at all.

But then you also had the whole "coke vs crack" thing in the 1980s - where crack was a predominantly used drug by ethnic minorities, and cocaine was more likely to be used by "high rollers" who could afford it - usually white and rich, yuppies, etc. Wall Street types and the like.

But rarely did you see or hear about any of those people landing in jail or prison for long periods. If you heard anything it was more or less laughed about, and society forgot about it. The perps maybe would spend a day or two in jail, get bailed out, and have their lawyers negotiate and plead down to a misdemeanor or something like that. Rich guy goes back to party and life.

Crack users? Well - they all ended up in prison for super long stretches and/or died there. Nobody cared or cares. Certainly not the above cocaine users and abiders.

It wouldn't surprise me to learn that the people abusing the cocaine and making deals like that weren't also in on the production and selling of the crack made from a portion of that same cocaine...

I'm not denying the double standard, just reiterating that some drugs are extremely harmful to people and their use should be discouraged/banned/whatever, no matter who is using them.