Here is a column by Jonathan Chait that I disagree with. His basic hypothesis, not very controversial, is that the basic alignment of US politics has not changed much over our history. There is a southern-centered tradition that is deeply distrustful of the federal government (and, to a lesser degree, of government in general), that is rural, white supremacist, and pro-military. There is also a New England-centered tradition that favors a strong federal government and public investment, champions racial minorities (sometimes rather paternalistically), and is skeptical of aggressive foreign policy unless there is a good reason for it. The party linked with each tradition has switched sides, but the two overall traditions remain.
There is some over simplification there, but yeah, basically. But then Chait identifies the Southern, rural, states rights viewpoint with conservative or "right wing" and the New England, pro-government, anti-racist viewpoint as liberal or "left wing." This is a serious over simplification. Other people have seen things in the opposite view, identifying the party of the left and the racist party together at least until WWII. Chait himself mentions Arthur Schlesinger's Age of Jackson, which salutes Jackson as the great democrat and champion of the common man and does its best to avoid talking about his white supremacism and Indian hating. Twenty years later the book Prelude to Civil War comments how often political figures who were "liberal" on economic policy were "conservative" on slavery -- and vice versa. And Ta-Nehisi Coates writes with deep grief about how some of the South's strongest supporters of the New Deal and railroad unions were also its most vicious racists.
To my mind, the answer once again is not to think in terms of left and right or liberal and conservative, but populist and non-populist. And populism fits poorly on a right-left spectrum. It leans left economically and right socially, both punches up and kicks down. Look at Andrew Jackson. He punched up at banks, corporations and speculators and kicked down at slaves and Indians.* Much the same can be said about the New Deal racists. They were economically liberal, supporters of the New Deal and the railroad unions, and socially conservative, meaning Protestant fundamentalist and opposed to liquor as well as upholding the racial hierarchy. The punched up against both local elites and national plutocrats. And they kicked down against black people.
Clearly there is a certain Southern populist strain that runs from Andrew Jackson down through the New Deal coalition and to the Tea Party today. Its opponents are centered in Greater New England and find such display vulgar. And there is no doubt that it has led to some very strange coalitions, particularly in the 1920's and '30's when the Democrats were both the party urban social liberals marked (in those days) as Catholic, pro-immigrant, and pro-alcohol (or anti-prohibition) with the South, the most Protestant, nativist, anti-alcohol region in the country. And although racial equality was having only its earliest stirrings, and only on the radical fringe, nonetheless, the mainstream groups most likely to be sympathetic and the ones most hostile were joined in the same party. The coalition couldn't hold for long.
So please, looking back at our past let us not try to divide the country into right and left, liberal and conservative and (above all) into good guys and bad guys. Accept that, for all their continuities, alliances are not always the same as they are now. But looking at the 19th Century in particular, instead of right and left, think populist and non-populist. And remember that, although populist is often used as a pejorative, it ultimately means holding one's self out as a champion on the common people. It can play to people's aspirations or to their resentments; it can either follow democratic rules of fair play, or champion outright mob rule. I firmly believe that a whole lot of political alignments are better understood when seen in those terms.
*Chait is right, however, that Jackson anticipated a weird right wing extreme libertarian pro-capitalist, hard money, anti-banking tradition that embodies the Austrian School of economics, the Mises Institute, Ron Paul, and so forth. I don't understand that tradition at all.