Thank you so very much for all of your wonderful advice!!! VERY much appreciated!!
I did contact the Onondago Library and got a speedy reply containing the NY State Death Index info on her:
Barrigar, Mildred A., died 10 April 1919, at E. Syr, #27700
so will send for the actual registration next week.
Thank you again!
Marg in Snowy Alberta, Canada