Could people stop with this insane idea that the Republicans were ever a "liberal" party in the American sense? They have been the party of big business and Wall Street from the 1870s to present. Hell, they weren't even "liberal" in the European sense in the 19th century: they were arch-protectionists and major supporters of high tariffs (both for protecting American business and for revenue purposes).
The big shift isn't in the party platforms so much as who made up the party. The mass defection of African-Americans from the GOP to the Dems from 1930s-1960s ended up making the Northern Democrats the party of civil rights (can't get elected in NY or IL or etc without the black vote), which alienated white conservative Southern Democrats and gradually pushed them into the GOP in the 1970s-2000s. It's inaccurate to say the parties "switched platforms" generally, though. The main groups that made up the GOP in the 1920s (big business, highly-paid professionals, Midwestern farmers) are still all mostly Republican groups, while the main groups behind Northern Democrats (recent immigrants, labor unionists, religious minorities, the poor) are mainly still Democratic voting blocs.
Most people can't see past "racist Alabama redneck voted Democrat in 1890, racist Alabama redneck voted Republican in 2016; conclusion: parties are opposite now."
LOL exactly.
One sentence argument: There has literally never been a time from the GOP's founding in the 1850s to present at which the Republican Party wasn't the party of Wall Street and Big Business.
Progressive Era.
and the GOP basically drove Teddy out of the party
In 1916, TR addressed the Progressive Party, stating that the best thing Progressives could do was to rejoin the GOP, which many did.