While nothing has been quite that "big" since then in the United States, the question is, why can't we find a way to come together without a global tragedy? A Newtown mass shooting and a Boston Marathon bombing later, we still can't seem to come together as a nation to make any progress.
I don't care where you stand politically, I just think we are all meant to take a minute on a day like today to remember what it felt like to work together, gain hope, and support one another. Let's close our mouths, open our minds, listen, and start working together. There are opportunities every day to start.
Be the change you wish to see in the world.