While eating a delicious currant scone from one of my favorite cafes, I looked it currants on Wikipedia and discovered some interesting history of why currants are popular in Britain, but not the United States:

During World War II, most fruits rich in vitamin C, such as oranges, became almost impossible to obtain in the United Kingdom. Since blackcurrant berries are a rich source of vitamin C and blackcurrant plants are suitable for growing in the UK climate, blackcurrant cultivation was encouraged by the British government. Soon, the yield of the nation’s crop increased significantly. From 1942 on, almost the entire British blackcurrant crop was made into blackcurrant syrup (or cordial) and distributed to the nation’s children free, giving rise to the lasting popularity of blackcurrant flavorings in Britain.

Blackcurrants were once popular in the United States as well, but became extremely rare in the 20th century after currant farming was banned in the early 1900s when blackcurrants, as a vector of white pine blister rust, were considered a threat to the U.S. logging industry. The federal ban on growing currants was shifted to individual States’ jurisdiction in 1966, and was lifted in New York State in 2003 through the efforts of horticulturist Greg Quinn. As a result, currant growing is making a comeback in New York, Vermont, Connecticut and Oregon. However, several statewide bans still exist including Maine, Massachusetts and New Hampshire. Since the federal ban ceased currant production anywhere in the U.S., the fruit is not well-known and has yet to reach the popularity that it had in 19th century United States or that it currently has in Europe. Since blackcurrants are a strong source of antioxidants and vitamins, awareness and popularity are once again growing, with a number of consumer products entering the market.