The answer isn't quite as obvious as you'd think!
When I grew up, we were taught that July 4th--Independence Day--was the day of the signing. As seen in the picture above, the story was that all of the Founding Fathers and Signatories got together on July 4th in Philadelphia, PA and signed this Declaration as a defiant act towards the king of England. This was the first, wonderful act of the revolution.
Of course, it wasn't quite like that.
If you searched for this image, you (Search-by-Image using the image-URL) you know it was painted by John Trumbull. His Declaration of Independence is a 12-by-18-foot oil-on-canvas painting in the United States Capitol that actually shows the presentation of the draft of the Declaration of Independence to Congress and NOT the signing. In fact, the painting actually shows the five-man drafting committee presenting their draft of the Declaration to the Congress, an event that took place on June 28, 1776, and not the signing of the document, which took place much later.
In an age before G+ and Facebook, Trumbull didn't actually know what everyone looked like. So when he made this painting (much after the tact), he could only show 42 of the 56 signers of the Declaration. (He also shows several participants in the debate who did not sign the document.) Interestingly, because the Declaration was debated multiple times and signed over a period of months, the men in the painting had never all been in the same room at the same time.
In fact, the simplest search
[ Declaration of Independence signed ]
In fact, Wikipedia article United States Declaration of Independence is pretty nice.
(If you look at the Talk page, you'll see it's been through a lot of revisions. As a side-effect, it's pretty much agreed-upon content. FWIW, the Talk page is a vast repository of interesting comments and side-stories about the Declaration. If you're a teacher in the US, I highly recommend the Talk section as a source of endlessly fascinating research topics for your students.)In any event, the Wikipedia article notes that the wording of the Declaration was approved on July 4, the date of its actual signing was August 2, although not everyone was about to sign on August 2, and the signing continued on for a while.
Oddly enough, for something so important, the original July 4 United States Declaration of Independence manuscript was lost. All other copies have been derived from this original document. (I'll let you look that story up on your own!)
But as you know from reading this blog, we always want to second source something like this. How can we find a source that would be credible and have really good information about the Declaration?
So looking farther down the SERP, I found a link from the National Archives (at www.Archives.gov). I'm probably going to believe what they say about the signing date. It's their job, after all.
They have an article entitled "Did you know Independence Day should actually be July 2?" Interesting. So opened that link to the Archives story. In there I found this quote:
July 2, 1776 is the day that the Continental Congress actually voted for independence. John Adams, in his writings, even noted that July 2 would be remembered in the annals of American history and would be marked with fireworks and celebrations. The written Declaration of Independence was dated July 4 but wasn't actually signed until August 2. Fifty-six delegates eventually signed the document, although all were not present on that day in August. (National Archives Press Release, June 1, 2005)
I should have guessed that the story would be more complicated than the simple one I was taught in school.
Search lesson: I told you this wouldn't be a hard search task, but I hope you take away the deeper lesson that you should double check even things you think you know. It seems non-obvious, but even history changes, or at least our understanding of what happened back then gets updated as we learn and understand the nuances more deeply with time.
Search on! (And double check those references!)
Have a great July 4th holiday! (For those of you reading this in the US... Apologies to readers from other lands. Send me a good search challenge about your national holiday and I'll put it in!)