If you asked them, most Americans would say that winning the Revolutionary War was the crucial step in the creation of the United States. The 13 colonies became a new nation once the British went home. Anyway, that’s the impression you’d get from the Wikipedia article about the Treaty of Paris, which put an end to the war eight years after the first shots were fired:
The Treaty of Paris, signed in Paris by representatives of King George III of Great Britain and representatives of the United States of America on September 3, 1783, ended the American Revolutionary War. The treaty set the boundaries between the British Empire and the United States, on lines “exceedingly generous” to the latter…. Only Article 1 of the treaty, which is the legal underpinning of United States’ existence as a sovereign country, remains in force.
But this is what Article 1 of the treaty says:
His Brittanic Majesty acknowledges the said United States, viz., New Hampshire, Massachusetts Bay, Rhode Island and Providence Plantations, Connecticut, [etc.], to be free sovereign and independent states, that he treats with them as such, and for himself, his heirs, and successors, relinquishes all claims to the government, propriety, and territorial rights of the same and every part thereof.
Listing all thirteen “sovereign and independent states” from New Hampshire in the north to Georgia in the south is an odd way to refer to a new nation. It made sense, however, because at that point the thirteen colonies considered themselves to be separate states or nations. The “United States” referred to the thirteen countries loosely joined together by the Articles of Confederation:
The Style of this Confederacy shall be “The United States of America”.
Each state retains its sovereignty, freedom, and independence, and every power, jurisdiction, and right, which is not by this Confederation expressly delegated to the United States, in Congress assembled.
The said States hereby severally enter into a firm league of friendship with each other, for their common defense, the security of their liberties, and their mutual and general welfare…
In his book The Quartet: Orchestrating the Second American Revolution, the historian Joseph Ellis says we should think of the United States at the end of the Revolutionary War as something like the European Union. I’d add that it was more like the EU plus NATO, but the point is that the people we call “Americans” considered themselves to be citizens of their respective states, not U.S. citizens. The colonists had banded together to win their independence from Great Britain. Having succeeded, they were willing to remain part of a “league of friendship”, but nothing more. Having won their freedom from a distant, centralized government, they didn’t want another one, even if the capital would be Philadelphia instead of London.
After what became known as “Shays’ Rebellion”, an armed anti-government uprising centered in western Massachusetts, some feared that the “league of friendship” would fall apart. According to Ellis:
[Some expected] the complete collapse of the confederation leading to civil wars between the states and predatory intrusions by European powers, chiefly Great Britain and Spain, eager to carve up the North American continent… The more realistic scenario was dissolution into two or three regional confederacies that created an American version of Europe. New England would become like Scandinavia, the middle states like western Europe, the states south of the Potomac like the Mediterranean countries.
The New England press enhanced the credibility of such prophecies, observing that the attempt at a national union was obviously a failure because regional differences made political consensus impossible. The only option was a union of the five New England states, “leaving the rest of the continent to pursue their own imbecilic and disjointed plans”.
It should be noted that even during the writing of the Articles of Confederation, the state of South Carolina threatened to walk away over the issue of slavery, a threat that was finally carried out when South Carolina seceded from the Union 80 years later.
Looking back, John Adams wondered how the colonies had ever agreed on anything:
The colonies had grown up under conditions so different, there was so great a variety of religions, they were composed of so many different nations, their customs, manners, habits had so little resemblance and their intercourse had been so rare, and their knowledge of each other so imperfect, that to unite them in the same principles … and the same system of action, was certainly a difficult enterprise.
Considering America’s subsequent history, including the regional conflict that led to the Civil War; the continuing resistance to Federal law in the southern states during Reconstruction and into the 20th century; the current division between consistently “Red” and “Blue” states; the popularity of right-wing news media that cater to a desire for “alternative facts” in opposition to what’s reported in the “mainstream” media; and the bizarre fact that we hold 51 elections, separately administered by the individual states, in order to elect a President, it’s fair to say that creating a United States that’s truly united continues to be a “difficult enterprise” and may never succeed.