I see arguments from both sides. One thing we can look at is party switching - some republicans switched to the DNC in 2016, and some democrats switched to the GOP in 2016.

But does that mean that the ideologies of the parties switched? As in, republicans once supported open borders, taxes, and gun control?

Some republicans refute this by showing the 1934 firearms act, and how southern states never voted in a republican governor until the late 90s/early 2000s.

Is it more that the democrats became more liberal and republicans became more conservative, or that the economic policies changed?