Final answer:
While 'Barbara Allan' is a well-known and widely-dispersed English-language folk song, it's challenging to crown it the most widespread due to the presence of other significant contenders. The song's popularity and endurance in the folk tradition are undisputed, but similar claims could be made for other folk songs.
Step-by-step explanation:
The question asks whether "Barbara Allan" is the most widespread folk song in the English language. "Barbara Allan" is indeed a very well-known traditional folk ballad that originated in Scotland and has been very popular in England and the United States, dating back to the 17th century. However, it is difficult to definitively declare any single folk song as the most widespread since there are many other contenders such as "Greensleeves," "Scarborough Fair," and "Amazing Grace" that have also seen wide dispersion and countless variations across English-speaking countries.
Folk music researchers often examine the popularity and dispersal of songs by looking at factors such as the number of recorded versions, the geographical spread of those versions, and the song's presence in oral tradition and literature. "Barbara Allan" certainly ranks high by these measures, with many artists contributing their interpretations over the centuries, but so do several others in the rich tapestry of English-language folk music. It remains a notable and enduring piece of the English folk music tradition.