On July 3, 1776, John Adams wrote two letters to his beloved Abigail exuberantly reporting that history had been made: One day earlier, the Continental Congress had voted to declare American independence from the British Empire. Henceforth, Adams predicted, July 2 would be celebrated by every generation with parades, speeches, songs and what he called “illuminations.” He got everything right, even the fireworks. But he got the date wrong.

Or perhaps we get the date wrong. The widespread assumption is that the Fourth of July is the day the Declaration of Independence was signed, the actual moment the founders pledged their lives, fortunes and sacred honor to the Great Question of Independence.

The popular musical “1776” dramatically depicts a signing ceremony on the Fourth. And the iconic painting “Declaration of Independence,” by John Trumbull, a version of which hangs in the Capitol Rotunda in Washington, is often captioned “July 4, 1776.”

But neither the musical nor the caption is historically correct. Trumbull’s picture depicts the moment on June 28 when the committee that drafted the declaration presented its work to John Hancock, chair of the Continental Congress. The play’s signing ceremony is theatrically compelling, but it never happened.

So why do we celebrate the Fourth? Because that is the day the declaration was sent to the printer, who then put that date on the top of the document, copies of which were distributed throughout the colonies and beyond. It became the date that readers then, and Americans ever since, recognized as the anniversary of American independence, even though nothing of historical significance actually occurred on that day. ...