at the forefront of a charge to save a piece of history from the bulldozers announcer: this is nbc nightly news with lester holt good evening as the nation turns the corner in the fight against covid, the thing that some experts believe has helped slow the spread, vaccine mandates, are facing the biggest challenge yet. the governor of texas tonight banning businesses and entities in his state from requiring proof of vaccination, setting the state on a collision course with the feds and leaving some companies that operate there caught in the middle. nationally, the number of fully vaccinated has inched up to 56.5%, leaving 67 million americans who are eligible for the shots unvaccinated even as attention turns again to booster shots for the already vaccinated miguel almaguer tells us more. reporter: even as some hospitals in hard-hit texas face another surge of covid cases, the governor here is issuing an executive order prohibiting any entity including private businesses from i