in Boston the generic term for soft drinks was tonic pronounced tawnic.
Ahhhh, yes indeedy! I took my tawnic to Houston in 1952 and got a befuddled look... tonic in Texas is on the order of Lydia Pinkham's Pills for Pale People.
As to ice cream based drinks.
In New England milk and ice cream whipped together is a frappe, but on a drive to west coast I learned to call it a "cabinet" somewhere in the mid-west.
Back in Boston if you ordered a "soda" you got syrup, carbonated soda and a scoop of ice cream perched precariously on the side of the glass.
In Pennsylvannia's Dutch Country (around Lancaster) I was introduced to Shoo Fly Pie, a molasses based pie which I've never found anywhere else. Yum.
To me the All American desert is apple pie. Whatever part of the USA you're in apple pie is apple pie! As in the euphemistic "war cry" -- "For God, Country, Mother and Apple Pie!"
wow
