Today is Flag Day, which in theory exists to commemorate the birth of the American flag on June 14, 1777. But the flag wasn't actually adopted that day—not in the sense that we think of when we hear the phrase "the flag." A former Reason editor explains:
In the early Republic, different people put forth all sorts of seals, mottoes and flags, representing both competing ideas of liberty and different graphic heritages. The Stars and Stripes, [David Hackett Fischer] notes, emerged as a national banner not out of an official committee but through a decentralized process of experimentation.
In 1777, the Continental Congress finally voted that the national flag should combine the red and white stripes used by Boston's Sons of Liberty with the star-strewn field of blue carried by George Washington's Army. But even that decree left the exact design open. "American citizens received it not as a fixed instruction but as an invitation to creativity," Fischer tells us. "The result was an outpouring of stripes and stars in many designs." Some flag makers arrayed the stars in rows, others in a circle, still others in an ellipse; five-, six- or seven-pointed stars appeared. Some flags included mottoes ("Virtue, Liberty, Independence"), additional images (the Liberty Tree) or the Masonically significant number 76. John Adams added the constellation Lyra to his version. Only in 1912 was the flag's form fixed by law, a symbol, unremarked by Fischer, of that centralizing era.
That's from Virginia Postrel's review of David Hackett Fischer's Liberty and Freedom; both the article and the book are worth reading in full. That spirit of centralization would soon intensify: From 1918 to 1920, it would become illegal to "willfully utter, print, write, or publish any disloyal, profane, scurrilous, or abusive language" about the flag. What had been a source of self-expression was now a center of censorship.