Which was more consequential: the bombing of Hiroshima or the moon landing?
Looking back on history, it's easy to decide. Hiroshima led to the end of World War II, the use of a powerful new weapon and the start of the Cold War, so it was clearly more important in the long run.
But things would look different if we were all living on a moon base right now. And they might look different in the future.
One year into the second Trump administration, it's hard to tell which of the president's many unprecedented actions may prove the most consequential. Will it be his revival of the long-dormant power to levy tariffs? His attempts to undermine the civil service? The aggressive expansion of immigration enforcement?
We don't know yet. A lot depends on what he does next, what Congress and the Supreme Court do, and how ordinary Americans respond.
Still, it's helpful to think about the question, so we asked some prominent historians and political scientists — including Heather Cox Richardson, Joanne B. Freeman and Brendan Nyhan — to share their thoughts on President Donald Trump's most consequential action of the last year.
Read the roundup of historians here.
