"There is a real place called Hoople, in North Dakota, spiritually not too far removed from the real Deadwood in South Dakota, though the two places are at opposite corners of the states. Hoople, however, is a tiny place even today (population about 300) and can hardly have been significant enough in 1876—even if it existed then—to be the source of a deprecatory comment."
"According to Professor Jonathan Lighter’s Historical Dictionary of American Slang, it probably derives from Major Hoople, who was a character in a once-famous cartoon strip entitled Our Boarding House, which featured the goings-on at Martha Hoople’s rooming establishment. It was written and drawn by Gene Ahern and began to appear in September 1921..."
"...It would not have been possible for Al Swearengen (Deadwood) to have used the word in 1876, 40+ years before Gene Ahern invented the character (Major Hoople) and a hundred years before it was first recorded in print. The producer and head of the scriptwriting team (HBO: Deadwood), David Milch, has been reported as saying in essence that he picked something out of the air to serve as a suitable insult without great concern for its etymology. It seems he must have heard it somewhere and it came conveniently back to mind while writing the scripts. It’s definitely an anachronism."
"Those damn writers on Deadwood don't research their slang words, but that doesn't stop Grandma from calling everyone a 'hoople head' anyways."