Conversation so far:
When did Rodgers and Hammerstein start developing Oklahoma?
Rodgers and Hammerstein started developing Oklahoma! in 1941.
How were the reviews at the New Haven tryout for Oklahoma?
The New Haven and Boston audiences were enthusiastic, although the reviews were only fair for Oklahoma.
What changes were made based in Oklahoma! on the reviews?
The addition of the show-stopping musical number, Oklahoma and the decision to retitle the musical after that number.
Were any songs cut before Oklahoma! opened on broadway?
What was the casting process for Oklahoma?
Between the world wars, roles in musicals were usually filled by actors who could sing, but Rodgers and Hammerstein chose, conversely, to cast singers for Oklahoma! who could act.
Were the leads for Oklahoma! known actors or new faces?
Hammerstein, with director Rouben Mamoulian's support, insisted that performers more dramatically appropriate for the roles be cast. As a result, there were no stars in the production, another unusual step.

Question: How did they find the actors for the show?
Self-contained rewrite: How did Hammerstein find the actors for Oklahoma?