This evening I was shelving books in our home library when I came across a volume of Bartlett's Quotations and upon flipping it open, saw this poem by Sarah Morgan Bryant Piatt (1836-1919):
My mother says I must not pass
Too near that glass;
She is afraid that I will see
A little witch that looks like me,
With a red mouth to whisper low
The very thing I should not know.
--The Witch in the Glass, 1888
Here's proof that looking glass legends have a long history in America! Or, Mrs. Piatt's husband served as American Consul to Ireland, so perhaps she picked up the story there.
The sum and total of my knowledge of Sarah Morgan Bryant Piatt.