Trivia

Died after surgery to repair smoke damage suffered in a fire in 1947.

He was continually disappointed and often upset by the major changes made by William Boyd to his "Hop-Along Cassidy" character. He had always envisioned Cassidy as a rough-and-tumble, hard-drinking and combative man and once said words to the effect that if Cassidy of the movies (an upright teetotaler who always stuck to a code of chivalry at all times) had ever strayed into the novels, the novel Cassidy's sidekicks would have shot him.

For a while he had no interest in meeting William Boyd, due to his anger at Boyd's interpretation of the Cassidy character. However, Boyd was finally able to arrange a meeting. Breaking the ice by saying to Mulford, "How are ya doing, you son of a bitch?", the two did manage to hit it off and a truce and friendship of sorts developed between them.

By the 1950s Mulford was no longer interested in writing any more Hopalong Cassidy novels. His publisher signed Louis L'Amour to write four books. After he signed, L'Amour found out the publisher wanted the William Boyd sanitized version of Cassidy instead of Mulford's rough-and-tumble version. L'Amour wrote the novels under the name "Tex Burns".