Party switches - a favorite discussion topic of Atlas (and myself, too).
Did the parties "switch platforms"? I mean, sort of; Karl Marx was a Republican, and there were plenty of left-anarchists in the GOP during the Civil War. Conversely, almost all of the outspoken racists left in America; the alt-right, the KKK, etc. now support the Republican party.
Democrats were once the party of classical liberalism and social conservatism. They were in favor of small-government values and free trade. The Bourbon Democrats, which ruled the party from post-Civil War to the late 1890s, are almost universally defined to be center-right.
But the Atlas RINOs have a point, and a damn good one. The Democrats have almost always had a more working-class, ethnic base, and they have always championed themselves as the savior of the common man. The Republicans have almost always basically been the party of big business.
Set the stage in the late 1890s. There are two major parties, which are both center-right and are basically in total agreement in terms of economic policy (with the exception of trade). The first truly left-wing political movement - the Greenback Party - tried to take hold in the 1880s. Due to the way that the political system was (and still is) set up, this third party could never actually take hold as a major political party. So - Plan B - integrate the ideas of the political movement into the major parties.
On the national level, the Democratic Party was the better selection at the time. Before the Civil War, it's populist platform was, in many respects, similar to that of the Greenback party; both Jefferson and Jackson, despite not being fond of each other at all, both believed very strongly in the
fundamental principle of preventing the concentration of power in the hands of the few. The Panic of 1893 completely shook up the political landscape; the Republicans had the largest gain in the House of Representatives in American history, and the Bourbon Democrats lost nearly all of their political influence in the party. This culminated in the 1896 nomination of William Jennings Bryan, who integrated the Greenback/Populist party platform and used the idea of Jacksonian Democracy to justify it.
At the same time, there were several Populist-Republican coalitions going on in the South. These were eventually crushed by the elite, planter-class, conservative Democrats, who enacted voter disenfranchisement laws that not only kept blacks, but poor whites as well, away from the polls.
But only about a decade later (so ~1910s), many race-baiting populist Democrats, who were
not economically conservative, use the votes of poor whites to get elected. The best examples of this are James K. Vardaman (D-MS) and Benjamin Tillman (D-SC).
Only a decade after that (so ~1920s-1930s), added to the mix of Southern Democrats were a handful of racially moderate populist Democrats. Prominent examples include Gov. Charles Hillman Brough (D-AR) who publicly supported anti-lynching laws and was even cross-endorsed by the GOP, Sen. Oscar Underwood (D-AL) who fought tooth-and-nail to curb KKK influence in Alabama and even served as Senate Minority Leader during the early 20s, and of course Huey Long (D-LA).
Of course, all the while, there were truly fiscally and socially conservative Democrats in the South, largely due to the one-party nature of the region at the time.
The issue of party-switching really comes with the question of race. Some modern Democratic social liberals want to separate themselves, and their party, from the Dixiecrat racists as much as possible, and so they say that the parties "completely switched" in the 1960s. Opportunist partisan Republican Trumptards want to argue how the Democrats are the
real racists. Both groups are wrong.
The GOP was, at its inception, extremely popular with African-Americans. The decline of support for African-Americans had really begun during the 1870s, when Rutherford B. Hayes brokered a deal to withdraw federal troops from the South. The GOP, at the time, had felt as if they had done enough for the African-Americans, and gave up on them as a constituency; though African-Americans were still staunchly Republican (for obvious reasons). After that, a strategy called the
Lily-White Movement was slowly taking hold, in which the Republican Party would attempt to appeal to white conservatives instead of African-Americans for their vote. It became their main electoral strategy in the South in the early 20th century.
By the 1920s, there were prominent racists in both parties. The Second KKK was not exclusive to the South; at one point, 15% of the American population was a part of the KKK. Denver had elected a Republican KKK mayor during this time. The final nail in the coffin for African-American support for the Republican Party was the election of 1928, and Herbert Hoover. Al Smith, being an urban Catholic who was against Prohibition, was very unpopular in the South for a Democrat at the time, and so Hoover went after Southern white votes hard. In conjunction with this (and arguably more importantly) were economic troubles; his mishandling of the Great Mississippi Flood of 1927 which left the African-American populated Delta economically devastated, and the whole Great Depression thing.
The New Deal had disproportionately benefited poor and working-class voters, and so they formed the new Democratic base. African-Americans were disproportionately poor at the time, and were able to get jobs in the WPA. Around the same time, a prominent liberal Northern Democratic wing was taking hold, one which was in favor of both Civil Rights and the New Deal. So, African-Americans in the North chose to vote for the Northern Democrats, despite being buddy-buddy with the Dixiecrats, over the Republicans who would cut the government spending that was keeping them afloat.
So, you can see how the parties did not
necessarily switch, but through the process of gradual realignments, ended up with different positions on the issues, and different party base demographics. Often the 1960s dominate the conversation, but the early 20th century was just as important in this gradual realignment of the two major parties.