Rodgers and Hammerstein's first Broadway musical was State Fair (Oklahoma, their second).
The second film version was the musical (the first, starring Will Rogers, was not a musical). As I recall, the son, Wayne, in the musical version for awhile wore a cardinal sweater with a gold "I". (The third film version, starring Pat Boone and Ann Margaret, was set in Texas.)
The Iowa specific song I recall was pretty corny (all I owe I owe Ioway ...). But like The Music Man, in a way all the songs were about Iowa.
I know old and tangential.
The book State Fair, which the film and Broadway versions were based on, was written by Iowa native Phil Stong. The "butter cow lady," Norma "Duffy" Lyon, who learned how to sculpt at ISU from Christian Petersen, as I recall, was his niece.