In general, what is the earliest you think the Civil War could have started to result in a Union victory?
Probably. It's worth noting that had the war begun in either of those years, less Southern states may secede considering that secessionist sentiment was much weaker in the Upper South prior to Harper's Ferry.
The Mexican War was 1846-1848. That was the spark that lit the long fuse. The earlier the date, the bigger the Union advantage. Remember, the best Generals are Winfield Scott and Zachary Taylor. In 1848, both are available in the field. Taylor died in 1850. Scott was too old in 1860. He could have done it in 1852, not sure about 1856.
There's a reason the Civil War happened when it did. It was the first time that the Presidency can be won without a single Southern state. Demographics would continue to move away from the slave states. Both sides are weaker materially the earlier you go, but the Union leadership is better.Hmm, see here I disagree. I would say the population, industrial and administration advantages that created the 'Yankee Leviathan ' grew out of growth that happened in the 1850's and such. The North-South divide is far less pronounced the farther back you go. This is setting aside what, I think, is the biggest issue. The will of the North to fight is the key to any possible Civil War. In OTL, they were willing to fight to the death, until nearly unconditional surrender. That is not the case in all TLs.
South Carolina flirted with the idea in OTL, and I'm not just talking about their being the first to actually secede either. I'm talking about during Andrew Jackson's presidency.It also would also be worth assuming other events post PoD would radicalize border states so they do leave. The lower south would not try to go it alone.
1832: Isn't that Jackson's Bizarre Adventure into the South, and his side wins easily? I think I had this discussion about a "Nullification War"; long story short, the Union still wins because of Andrew Jackson...What about a less-discussed date: 1832? At that point, South Carolina adopted the Ordinance of Nullification which nullified the Tariffs of 1828 and 1832. If more states were on the same page as South Carolina, then you could get a civil war even before 1848. Whether or not the Union wins, IDK for sure.