When we lived in Rochester, New York, one of our neighbors grew red and black currant bushes in her backyard, and shared them with us. Sadly, she moved away soon after we become acquainted, and the bushes were removed. At the time, I thought the new residents just didn't want to bother with them, but maybe they knew something I didn't:
The plants were illegal. Here's the story. (17 minutes at normal speed)
In brief: Plants of the genus Ribes, which also includes gooseberries, are susceptible to a fungus that also produces white pine blister rust, which in the early 1900's was devastating our white pine trees.
Apparently the lumber industry had a more vigorous lobby than the gooseberry family, and our federal government both outlawed the Ribes family and began a massive program of eradication. If it had been the 21st century, gooseberry fans would have been demonetized on YouTube and banned from Twitter.
The federal regulations against Ribes were lifted in 1966, but many states still prohibit or restrict it. My neighbor's yard didn't become a legal site until 2003, and many places in New York still aren't. Here's an interesting list of state regulations. My favorite may be Pennsylvania: "In 1933, Pennsylvania passed a law that limited growing gooseberries and currants in certain areas; however, the law is not enforced. Therefore, all Ribes can be grown in the state."
(It must be pointed out, however, that laws that are traditionally not enforced can still be a threat. if your name is Donald Trump, growing currants in Pennsylvania might still land you in court faster than you can eat one.)
Back in the early 1900's, national governments apparently felt they were faced with a stark choice: save the pine trees, or save the currants and gooseberries. The United States chose lumber; Europe chose food. Both are important, of course, but in hindsight it seems clear that letting nature take its course might have been best. When governments take to using hatchets when flyswatters will do, bad things happen. In subsequent years, better approaches to the white pine blister rust problem have been developed. I suspect these developments would have come sooner if we hadn't decided to commit plant genocide instead.
Because of their great nutritional benefits, Ribes, especially black currants, are making a slow comeback. But I've never seen them in our local grocery store. For that, so far I still need to make a trip to Europe, where currants and gooseberries are easily found.
You might enjoy the post I wrote 13 years ago about my visit to a farm near Basel, Switzerland, where I was allowed to taste freely of gooseberries, three colors of currants, and other marvelous fruits that are difficult to procure here.
UPDATE 1: I have it on good authority that there's at least one farm in New Jersey where I can pick gooseberries and currants if I'm passing through at the right time. It would be interesting to know if "currants" listed on their website also includes the black variety, which New Jersey still heavily restricts—that is, if the Wikipedia article is correct, which is a risky assumption, though less so with currants than with current events).
UPDATE 2: Do not be confused by what are called Zante currants, which look like mini-raisins and are made from small grapes. You can find Ribes black currant products on amazon.com, but a search is more likely to misdirect you, if that's what you're looking for.
UPDATE 3: In the United Kingdom, Australia, and no doubt some other parts of the world, purple Skittles candies are black current flavored. In the United States, the flavor is grape. Not content with trying to eradicate the plant itself, we seem intent on eradicating America's taste for the fruit.