A resemblance of the form of the first verse of "Rio Grande" in Carmina Princetonia to that of the ballad, "The Milk Maid":

Where are you going to my pretty fair maid
With your red rosy cheeks and your coal blach hair
I'm going a milking, kind sir, she answered me
Rolling on the dew makes the milk maid fair.

Harding B11 (2422). Between 1821-1850, Bodleian Library
http://bodley.ox.ac.uk/ballads/ballads.htm.

No real relationship, but "where are you going my pretty fair maid" begins several old broadsides.