Could this be?
No, with a probability of 99 percent. To win the Confederation would require extraordinary circumstances. For example, the intervention in the war of some of the European superpowers, and it is on the side of the South. For example, if the UK for some reason it would be needed. This development was unlikely. First, Europe had more important things to do than any civil wars there in a distant country at that End of the World. Secondly, no one would openly support those who are fighting for the preservation of slavery. Europe strongly condemned him at the Vienna Congress in 1814. And then everything is very simple. If you supported slave-owners, even for some other reason, then you crossed out a whole multitude of international agreements and gave the opponents a reason to create a union against you. Who needed it? No one.
Rally in support of Lincoln's recruitment of volunteers
The North had too many advantages. The economic advantage, a more technically developed army, international support (verbal approval only) and even numerical superiority (23 million inhabitants, against 9). Not to mention the fact that after the slave-owning states left the Congress, all the authorities and complete freedom in the adoption of new laws remained in the hands of the “Yankees”. Including those that have complicated the life of the South. And we have not said anything about tens of thousands of slaves on the plantations of the Confederation. They are a kind of time bomb in the rear of the army of the South.
Little touch: many wanted war. And it is in the midst of ordinary Americans. In support of the Lincoln Declaration on the recruitment of volunteers, many thousands of meetings were held. You can, of course, assume that state employees were driven there, only in those times there were no state employees in the USA ...
Scenario one. Possible
The South could not have won the war, but could probably not lose it under certain circumstances. For example, it is known that four slave states (Delaware, Kentucky, Missouri, and Maryland) remained part of the United States and were not part of the Confederation. This is quite an important circumstance. The balance of 13 states against 23 in favor of the “Yankee” would have changed by 17 against 19. In such a situation, the slave-owning states might not even have had to leave Congress. It is important. After all, the exit of the southern states from the state gave the North an almost perfect excuse for the start of the war: “The withdrawal of the state from the Union is contrary to the Constitution.” Not to mention that the front line would move strongly to the North, and Washington would be surrounded on all sides by the territories of the Confederation. That is, as a last resort, brute force could be applied to Congress.
Plus, of course, let's not forget about West Virginia, which separated from the state, deciding to remain in the Union. Just strategically: the presence of this territory as part of the Confederation would give the army of the South an opportunity to launch a lightning invasion of Pennsylvania. There is a possibility that, with such starting positions, the generals, loyal to President Lincoln, would convince him that the war might end in disrepair.
General William Tecumseh Sherman. He revived the scary earth scary tactics for the present.
In this scenario, the South and the North would have to look for some compromises and opportunities for dialogue. For a start, this would lead to the fact that the new states would be decisively and permanently banned from making their own decisions about slavery on their territory. Until 1854, a law was in force in the United States, according to which new states were accepted into the state in pairs. One free, one slave. Most likely, this rule would save power.
The second point, no less important. The departure of the slave states from Congress unleashed the North in matters of legislation. Lincoln took advantage of this situation to conduct a number of important laws for the development of the economy and society through Congress. For example, the Law on Homesteads, which gave large segments of the US population the opportunity to get their own land. Or the "Law on Banks", which allowed the United States to create its own banking system. Or the “Morilla Act” which laid the foundation for vocational education in the country. All these laws would not exist, the slaveholders would maintain their position in Congress. Simply put, the country's economic growth would slow down, and the influx of migrants from Europe would decline. Large segments of the population would not have the opportunity for self-development and improvement of living conditions. The bottom line is the likely economic crisis and depression.
Finally, the third point is extremely important. The model of peaceful existence of the South and North prevented the creation of the internal market. All products manufactured by the South were not focused on domestic trade. Cotton from the plantations went mainly to Europe. From Europe, however, Louisiana, Florida, and other slave states received everything they needed for their existence. In fact, this made the future Confederate lobbyists of free trade and opponents of high duties on the importation of goods. As for the North, industrial growth gave it less than it could have given, because the sales market was limited only to free states. If such a situation persisted even after 1865, the industrial boom would be replaced by an industrial recession.
Scenario two. Utopian
Complete victory of the South in the war. Very unlikely, but consider this option. Here it would not be limited to what is described in the previous part. A total victory for the South would mean the resignation of Lincoln and, most likely, the complete collapse of the Republican Party. The spread of slavery throughout the United States.
What changes it would cause. First, a huge surge in the slave trade. Now slaves would be required not only for plantations in the south, but for plants and factories in the north. For the construction of new railways, for mining companies, for urban construction and much more. The number of unfree US residents would rather quickly exceed the number of planters and free people. Sooner or later there would be a stratum of dark-skinned people who are not in slavery. A sort of semi-serf.
Battle of Entity One of the most famous battles of the Civil War, not counting Gettysburg
But the migrants would not have become completely. Why go to the US if there is no work. Europeans would leave in search of happiness in South America, also in dire need of labor. By the way, slavery there began to abolish earlier than in the United States. Brazil got rid of him in 1809. Most likely, fugitive slaves from the USA would also strive to get there by any means. Surviving abolitionists would have moved there.
Possible outcome. The economic decline of the United States in exchange for rapid economic growth in Brazil. Who knows, maybe now the leading state of the world would be the country of carnivals, the Amazon and Pele with Ronaldo.
By the beginning of the twentieth century, the United States with the victorious slavery would be an economically backward agrarian state, unable to provide itself with everything necessary. With a fall in cotton prices, the country would have torn the crisis. While maintaining high prices, the United States would become an ideal market. Products from all over Europe would be imported here. Great Britain and Germany would be greatly enriched, France and Russia would also be pretty bad. Alaska, most likely, would remain within the Russian Empire, which would hardly have found a buyer for it.
Jefferson Davis could be the real president of the United States
Who knows, maybe if Europe had such a market, then there would be no First World War. On the other hand, if it had nevertheless happened, no United States would have entered it in 1917. Or they would have entered only formally, sending two or three regiments of soldiers to Europe, for show. As a result, France would not have received colossal support on the Western Front. Not a million soldiers from America, no economic aid. Could not even withstand the pressure of the German Empire. But blow through the Germany of the Western Front as she wanted to break through it, and the First World War would have ended completely differently.