Officials warn of massive crowds for MLK dedication

District officials are warning Washington residents to prepare for massive crowds expected to hit the National Mall not only on the day the Martin Luther King Jr. Memorial is officially unveiled, but also on the days leading up to it. More than 200,000 people are expected to attend when President Obama speaks at the memorial’s official dedication on Aug. 28, potentially causing massive lines at Metro stations and gridlock in and around the Mall, officials warned Tuesday.