All ballots cast during the extended early voting hours are provisional, to comply with federal law. That's because they'll have to cast provisional ballots, a process that involves extra steps. A court order extended early voting in the runoff election after polling locations were closed Sunday and Monday due to a winter storm. The 18th Congressional District stretches from northern Harris County to areas north, south, east and west of downtown Houston. A full list of early voting polling sites can be found on the Harris County Clerk’s elections website.