As I recall the first nine was built in 1937 and the second in 1957. So it really is a 1937 course since the second nine followed the look of the first.
Prairie Dunes
It's your thread, JW, but I'll respectfully disagree. When the club raised the money in '55 to create an 18-hole course, Press Maxwell added holes 3, 4, 5, 11, 12, 13, 14, 15, and 16. The club could have hired Joe Finger or RTJ or anyone else to lay out 18 holes, but Prairie Dunes Inc.
chose Press Maxwell, and his final 18 routing dates to 1957.
Similarly, Garden City GC dates it founding to 1899, because that is when all 18 holes were laid out; and yet Emmet completed the original Island Links nine in 1897.