This--before both of the above--is from the St. Louis Post-Dispatch,
"Answers to Queries," 11 February 1917, pg. 2, col. 6:
F. B. J.--Pronunciation of St. Louis has not been fixed by law. Western
people say Saint Loois; Eastern, Saint Loo-ee; Frenchmen, San Loo-ee; Germans
could say St. Ludwig. "Saint Looey" was the pronunciation used in the Masque
of St. Louis, the symbolic afterpiece of the Pageant in Forest Park, May
23-31, 1914. Percy MacKaye, writer of the Masque, said the name of St. Louis
would be shouted by many voices in the latter part of the Masque, as the
nations of the world, and the other cities of America, hailed the knightly
figure representing this city. These shouts should sound over the hillside
in the largest possible volume and for that prupose he decided that it would
not do to have an "s" sound on the end of the word. Although the
poet-dramatist did not mention it, a precedent for his choice of the "Looey"
pronunciation was set by the writer of a popular song of World's Fair days.
The song was entitled, "Meet Me in St. Louis, Louis," and a footnote
instructed the singer that "Louis" should in both cases be pronounced
"Looey."
Judy Garland still won't meet me--Saint Looey, Mizzourah, wherever it
is.