I think this is absolutely correct. Prosperity begats Liberalism.
The planter class was crushed by the war. Had the war not happened, they would have been ruling for a long time. This would not have been acceptable to the midwestern states. Take the time if you have it to look up what South Carolina politics were like before the Civil War. That is not something that would be appealing to any people with free and democratic traditions.
I have said more than once that the Southern Aristocracy were @$$holes, and that I would likely have hated them had they become dominant, as much as I currently do the New York/ Washington DC Aristocracy.
You apparently still think that the 2004 election was the template for all American politics.
I think the map of the 2004 election illustrates the likely societal and political changes that would have occurred with the CSA continuing to exist. I think that all those states have more in common with each other than they do with the New York Aristocracy, and they would have eventually formed a political coalition together.
But it took time for the Southern and Plains states to come together politically. The South had to get rid of slavery and segregation.
I see that as all inevitable.
The Germans and Scandinavians of the Plains had to become assimilated and lose their European ways. Southerners a century and a half ago didn't much love the Germans. Neoconfederates today are forever maligning them as early socialists, wrongly but not entirely without reason. All that would have to change, and as recently as half-century ago, the Upper Plains were more Mondale, McGovern, and Humphrey than anything else.
Yes, the Germans and Scandinavians do have too much fondness for socialism, but this I think is the consequence of their homogeneous background. "Socialism" appears to me to be adopting the ideas of a family unit onto a larger scale, and it is more workable and less objectionable among groups that share the same genetic background because it's basically an extension of a "family".
Germans and Scandinavians also seem to have a fondness for authoritarianism too, and that has been another difficulty with integrating them into the American mindset. But all that slowly evolves in line with the social environment in which they find themselves.
Tariffs weren't the big determining factor that you believe they were.
"Tariffs" are an imprecise term for the larger effects of economic changes which would have occurred from secession. "Tariffs" are misleading in this context because the changes from secession go way beyond tariffs. It's just become popular to encapsulate all these ideas under the title of "tariffs", but it is very misleading.
Moreover, tariffs only went up as high as they did because of the necessity of paying for the war. And they only stayed up as high as they did because the Democrats had become identified as the party of rebellion.
Ha! Pull the other one! It is inherent in the history of government that once they get a tax, it becomes nearly impossible to take it away from them again. When you are exercising great power and influence by taxing some to spend on others, your power is diminished if taxation is diminished.
If farmers were discontented, they would work within the political system to redress their grievances, something Southern planters didn't want to do.
Hardly. They would try to go around the system. See "Grainger movement."
Forms of slavery had been around in the area for centuries, and given a pro-slavery national government, slavery would have continued and been expanded.
Doing what? What would pay the slave owner more than cotton?
Given the complexity, I don't see how anyone can have the confidence in their own predictions that you have.
I have great confidence in predicting that people will gravitate towards money and self interest. I believe this is inherent in human nature.
Here is a graph indicating US tariffs in the 19th century:

We see that the tariff went up to fight the war and pay for the war debt and then went down as "normal" politics with two party competition reasserted itself in the 1880s. That is essentially also what happened before the Civil War and what one would expect to happen (without the initial increase being as high as it was) had the Civil War never happened.
Facts and data are of more value than a priori assumptions. Nineteenth century Americans were more self-reliant and there wasn't the culture of dependency you see today. Americans were used to less government than they are now, so taxes and the size of government could still go up and down. But if you want to make abstract assumptions, you ought to admit that they would have applied to the CSA as they did to the USA.
Hardly. They would try to go around the system. See "Grainger movement."
The Grangers, the Populists, the Non-Partisan League all worked within the system in the sense that they didn't try to overthrow the government or secede from the rest of the country.
Doing what? What would pay the slave owner more than cotton?
I'm going to assume that tobacco, hemp, sugar, domestic service, heavy lifting, carpentry, construction, wagon-making, leatherwork, and all the other things slaves did in the South before the Civil War didn't bring in as much as cotton, yet slaves were applied to all those activities. Maybe some of those activities actually did bring slaveowners more money than cotton growing. After all, there are expenses attached to cotton growing that slaveowners who rent out their slaves don't have to pay.
Slavery was unprofitable in the Northern states so it was abolished. It wasn't that profitable in some Southern states either, but the political will was there to keep it in place, so it wasn't abolished. And the Confederacy definitely had the will to keep slavery going and even to spread it. Also, if you had slaves, you could always sell the ones you didn't need to other slaveowners. That kept slavery going in many areas of the South.
The country was founded as a Christian nation, and those who don't like it really have no legitimate recourse in the same manner that it was founded as a slave nation, and those who didn't like it had no legitimate recourse.
Many people then, and some now, believed that the country was founded as a free, as well as a Christian nation, some believing that because we were Christian we had to be devoted to freedom. Was any of these assumptions -- that the country was founded on Christianity or on freedom or on slavery -- more solidly and unshakably founded than the others? You, choosing always the letter of the law, would probably want to say slavery was. The founders and many of their 19th century descendants would have disagreed, slavery being something the country had trouble getting rid of, not something that defined its essence.
When it became clear to them that they were going to lose in the financial game, they then needed government to rescue them from the free market.
It would be nice if you had some evidence for that, but it looks like it's more abstract speculation based on generalities, rather than evidence. Fernando Wood, the mayor of New York and a very wealthy man, wanted New York City to maintain its commercial ties with the South and secede from the US to become independent. Other wealthy New York merchants disagreed with him about the city seceding, but very definitely wanted to maintain their commercial ties with the South. Those ties were close and amicable, secessionist propaganda notwithstanding.
New Yorkers had the financial skills and weren't especially worried about some Southern city displacing them as the continent's leading port. Things like that take time, and resourceful people have ways of landing on their feet.
And why hadn't Halifax or Montreal replaced New York? They were open to British goods without tariffs or duties. They had a long border with the US that wasn't very well controlled. What you say about the South applied to Canada as well, but New York had the population, the rail network and the commercial and industrial skills to keep going and stay on top economically.
Your assumption that the political moves you favor represent the "free market" is also problematic. Opening up our borders to Chinese goods today represents the "free market" for some people. Same thing with opening up our borders to the uncontrolled movement of people. Is that a good thing? Is wanting some control or protectionism a bad thing? So no, it's questionable whether tearing the country apart or turning its economy and society upside-down really represents the "free market" and not an act of political power.
The Democrat party has been quite protectionist for most of my life. It is only with the advent of Chinese influence on major corporations and players in Washington that the Democrats have seemingly backed away from protectionism and are now reflecting corporate interests above that of their Unionized rank and file.
You must have had a very short or a very strange life. Kennedy and Johnson pushed for tariff reductions. So did Bill Clinton. I would argue that it was more Republicans who lost their way in the Bush era.
Elizabeth Cady Stanton. Margret Sanger. Susan B. Anthony. Jane Addams. Louis Brandeis. Florence Kelley. Roger Baldwin. And so forth. Virtually everyone in the progressive movement was a Republican and from the North, usually big cities.
Were Stanton and Anthony "progressives" in any modern sense? How "progressive" was Jane Addams, who endorsed Hoover over Roosevelt? Roger N. Baldwin (the founder of the ACLU, not to be confused with an earlier Roger S. Baldwin) was not a Republican. Florence Kelley was likewise a socialist. I learn today that she was a fighter for an eight-hour day and against child labor. Would you really be on the other side of those fights?
But of course, in the early years of the Twentieth Century, the South did have its own populists and progressives, supporters of Wilson and FDR, advocates of women's suffrage (if that's a bad thing) and income taxes to soak the Northeastern states. What they didn't have much of were big cities and urban problems and social workers. If they had had more big cities, they would have had their own Jane Addams and their own settlement houses and their own child labor legislation.
Your argument is circular and nonsensical. You admit that cities encourage liberalism or progressivism. Then you attack Northerners for having cities and having reform-minded characters. But by your own admission, that is the way the world is. And it's not even a question of North and South (or increasingly of urban and rural). The South has its own liberals and progressives. That's not something that can be avoided in the modern world.
Yes, because it had become politically popular. Had it not turned out to be, it would have been left by the wayside. Part of the reason it had become politically popular is because Lincoln tended to arrest people who didn't toe the official government line.
Men fighting against slavery were dying for freedom so freedom became an issue. It wasn't about "political popularity," it was a matter of respect for the sacrifices soldiers were making.