California Code, Elections Code - ELEC § 13214

The left-hand side of the first column of names on the ballot and the right-hand side of the last column of voting targets on the ballot shall be bordered. The binding or stitching of each package of ballots shall be along the top or head of the ballot.If ballots are to be used on a ballot on demand system or another system that prints content onto ballots, ballots are not required to be bound or stitched.