It's America's most important holiday. Did you even know?

A little-known U.S. holiday with deep historical roots remains largely overlooked by the public despite its significance. Officially recognized only in 2004 through legislative action, it honors a pivotal moment in American history tied to the end of slavery. Unlike major federal holidays, it carries no mandatory day off, leaving many unaware of its existence or meaning. The holiday’s obscurity contrasts sharply with its importance in marking a turning point in the nation’s struggle for equality.

The most important national holiday in the U.S. doesn't earn its citizens a day off from work or school. It wasn't formally created until 2004, when Sen. Robert Byrd (D-W.Va.) quietly inserted it into an omnibus spending bill. Most Americans have no idea when it is celebrated or even what it commemorates. And yet, given...