Upvote:3
1918 was during the Fourth Party System that was in effect from 1896 to 1928. Under this system, the Republican party was principally a party of business interests and skilled workers, along with what few African-Americans were allowed to vote, while the Democratic party was a coalition of white supremacists (particularly in the South), unskilled workers, and immigrants. The Republicans usually had the upper hand, with only one Democrat elected POTUS during this period.
Political map of the 4th Party system. The darker the shade, the more likely the state was to vote for that party's candidate.
With these coalitions there were wings in both parties in support and in opposition to many national issues. The big issues that starkly separated them was tariffs (protectionism) and the handling of the monetary system. But if those are not issues that get you going like it did people at that time, then both parties would look rather diverse. Both parties had what we'd today call "conservatives" (Republican business interests, Democratic White Supremacists) and "liberals" (Republican progressives, Democratic Labor and Immigrant interests).
However, if those (now rather arcane-looking) macroeconomic issues were your primary political animation, the parties would look quite divided.
The subsequent Fifth ("New Deal") System saw black voters switch en-masse to the Democrats, and the White Supremacists start to drift away from them. With the Sixth (arguably the current system) the White Supremacist wing fully switched parties, while the Progressive Republicans switched the other way, and that is how we got to the current situation where one party is a coalition of pretty much all the nation's "conservative" interests, while the other has everyone else.