Worst year of the US history

[Unconditional Surrender Truman]

This list suffers from a powerful recency bias, but of the dates listed (and probably of those not listed) I voted for 1862, which was arguably the last time when the U.S. could plausibly have ceased to exist.

[Unconditional Surrender Truman]

Of those on the list: 1862 for the reasons Truman and others aid.

Not on the list, but late 1776 and winter 1780-1781.

These were desperate periods where the Revolution could have been lost. In the former, just prior to the battle of Trenton, Washington had been severely reduced in men and had lost NYC and most of NJ to the enemy and there was nothing to stop the British from taking Philly. While Philly did fall the next year, the Americans defeated the British at Saratoga.

In the winter of 1780-1781, things were desperate for the Army, The country was basically bankrupt with the economy in ruins and the South was occupied. While the French were sending help, it was not nearly enough to continue indefinitely and they had just come off the treason of Benedict Arnold. 1781 was really a do or die time for the American Revolution with the victories at Cowpens and then finally Yorktown ending the Southern phase of the War and convincing the British to give up on the 13 colonies and focus on defeating the French, Spanish and Dutch.

It's remarkable how physically close Washington came to being captured in the last four months of 1776, literally coming within feet of the British forces during the retreat from Long Island. If not for the sheer arrogance of Howe and his officers returning to New York for the winter rather than continuing to pursue the Continentals, U.S. history would be six months from July 1776 to January 1777.

[Unconditional Surrender Truman]

This list suffers from a powerful recency bias, but of the dates listed (and probably of those not listed) I voted for 1862, which was arguably the last time when the U.S. could plausibly have ceased to exist.

Even if the Confederacy had won it is not like the rest of the United States would have broken up? The country would obviously be a lot different, but it is not like the US would cease to exist. If anything I'd say the last time the US could have ceased to exist was when it was fighting the war of independence (even the 1812 war was in self-defence from Canada's perspective and Britain had 0 interest in reconquering the US?)

The US would still exist to this day, with still most of their current territory (minus the confederacy obviously) and would have still been the number 1 superpower for much of the 20th century, though the Cold War would have been closer and I suppose China would have already beaten the US in terms of power at the turn of the century but the US would still be a comfortable number 2.

That all assumes history still goes through a similar path as we know beyond the Civil War of course which is a big stretch but still.

It really is. Taking it for granted that the U.S. would keep control of its OTL territory minus the eleven Confederate states is a dubious assumption at best. We know in reality that the Confederacy coveted the Southwest, while the border states (particularly Missouri) would have remained sharply divided. (It's not difficult to imagine St. Louis as a kind of North American Alsace-Lorraine.) Meanwhile, an independent South means the Midwest no longer has free access to the Gulf via the Mississippi River, with enormous implications for the post-war economy. In short, even if there were no more secessions after 1861 (a very big if when one considers the many secessionist plots simmering in California and the Midwest), a Confederate victory would change the North American political and commercial landscape dramatically. Partisan politics would be similarly effected: without the Solid South, the Democracy would need to evolve to appeal to new constituencies, and it's likely "waving the bloody shirt" has a very different connotation ITTL. That's not even to mention the foreign policy implications: does a United States with a powerful, hostile neighbor on its Southern border (possibly with the diplomatic and/or military support of Britain and France) still pursue imperialism in the later nineteenth century; or does it instead focus on mustering its military and industrial strength for a reconquista? How does that impact WWI and beyond? (If the U.S. never acquires Hawai'i, do we still intervene in WWII, assuming there is a WWII.)

All of this is counterfactual, obviously, but handwaving the breakup of the Union as a minor obstacle to the progress of history as we know it strikes me as frankly ignorant of what was actually at stake in 1862 and how the American Civil War differs from European separatist wars.