As Eva Lawrence points out, it depends on when and where. But I would suggest you check FamilySearch.org. They have voter registration lists from a lot of places in the United States (and, I would assume, other countries as well) for a variety of time periods. Do a records search for your grandmother, and when the results display, go to the collections tab to narrow the results to voter lists from her place of residence.
Deborah Blankenberg (JewishGen ID #613395)
Researching BLOCH/BLOCK (Germany to New York, Colombia and Missouri), BLINDER (Kishinev to New York via Poland? and Paris), KUSHER/KUSZER (Lodz vicinity to New York via Paris), GOLDSCHMIDT (Germany)