Indeed it could have. The union could have actually tried to enforce the “forty acres and a mule” notion some of the more radical republicans wanted. As well as remaining longer.*
*its a common criticism today that the north didn’t finish reconstruction. Because obviously union troops there longer would have prevented the violence against freed slaves.
In fact it’s basically orthodoxy amongst progressive historians.
This ignores that a continued union occupation would have engendered even greater animosity and after all-it would have given southerners the impression they were a nation, just a defeated one.
(as an aside I got into a lot of heat on SB for this-for arguing the Dunning school wasn’t as wrong as modern historians claim).
Of course the south could have continued to wage guerrilla warfare, alongside fighting the freed blacks and unionists-turning the south into Sudan which had ongoing civil wars and ethnic violence from the time of its independence in the fifties until IIRC 2002. Imagine reconstruction era political violence going on to the 1920s. This I find very likely in a worst case “union tries to enforce reconstruction longer scenario).
The war could have developed more WW1 characteristics and became a stalemate with larger casualties.
But yes the war could have been much worse. The US so happened to be entering the height of the age of industry and capitalism after it. With the railroads, and steam power alongside a vast internal market.
It makes me question barring some mutual collapse just how bad the war could have gotten. At least due to long term economic trends.
But that is an aside on my part.
A civil war in the vein of Syria, Colombia, or Spain today-would not be so easily rectified. And would leave the country devastated, it’s power and prestige gone, it’s cities in ruins and it’s people broken.
But we are still yet far away from that outcome.