Time:

The month of July is a time for Americans to look back at the country’s past—specifically to that indelible moment in 1776 when the Second Continental Congress declared independence from Britain. But, while the nearly 250 years since then have been chock full of major milestones, not every moment that shaped the country gets the credit it deserves.

With that in mind, TIME asked 15 experts to each nominate an unsung moment from American history. These are events that, though not necessarily widely known today, either changed the national story in some important way or embodied a significant current. And if you don’t know about them yet, these historians will explain why they think you should.