We mark the 20th anniversary of the 9/11 attacks, and mourn the nearly 3,000 lives taken too soon. The people who perished in the World Trade Center, the Pentagon, and Shanksville—including the heroic first responders who gave their lives to help others—left behind loved ones and communities who were never again the same. In the years since, more than 2,000 more were lost to 9/11-related illnesses as a result of working in hazardous conditions during recovery operations. We honor their lives and their memory on this solemn occasion, and mourn what we all lost on that terrible day.