According to the Onondaga County Board of Elections, any pen will work, but they do recommend blue or blank ink. No need to use a Sharpie.

Some posts say using a Sharpie on your ballot will invalidate your vote. But many ballot tabulator manufacturers actually recommend Sharpies over regular pens.

The preferred method would be a black or blue ink pen, but a Sharpie will work.” Davidsen: “If you use a Sharpie, what happens if it bleeds through?” Nicolay: “If it bleeds through, nothing.

They said the pens "are recommended by the manufacturer because they provide the fastest-drying ink." In Pennsylvania, elections officials in Montgomery County supply Sharpie pens to all precincts.