District 1 - GIAC, 300 W. Court Street (on the map it's the blue star with "D")
District 2 - Titus Towers II, 798 S. Plain Street (the blue star with "B")
District 3 - GIAC, 300 W. Court Street (the blue star with "D")
District 4 - TC Public Library, 101 E. Green St. (the blue star with "E")

This map is from the Tompkins County website's "Map Library." That's the site to go to if you want to know detailed boundaries and voting locations of other districts and jurisdictions in Tompkins county.