A lien is a claim placed on someone's property as security for the payment of a debt. A property owner would have wanted to pay their tax to avoid having a lien placed on their property and would have been aware that the tax was due. Non-property owners would have been less aware, and, unlike with property owners, no process existed to enforce the paying of the tax. Why might African American voters have been more affected by the effects of a poll tax than white voters?