Anti-federalism -- Deep rooted distrust of the Federal Government has been around since the dawn of the USA, though its often been part of the minority.
Know Nothing / Native American Party -- 1850s era movement. Protectionist, isolationist, nativist. Originally they popped up as anti-Irish and anti-Catholic, but overall the concept is that immigrants suck. The modern concept is: "I know nothing", about the movement. The overall idea is that even in the 1800s, it was bad to look like a racist bigot, so you'd keep your support for these causes secret. Everyone in the party knows that "the Know Nothings are larger than everyone expects", but no one really knows how big the movement is. And that's the point.
America First -- 1930s saw the rise of Fascism vs Communism in Europe with the dawn of the Spanish civil war. The "America First" movement focused on isolationism and even pro-German / Nazi slant mixed with religious fervor. This was pushed by tech-gurus of the time: Charles Lindberg (airplane entrepreneur, first Trans-atlantic flight, etc. etc.), and the Christian Front. (https://en.wikipedia.org/wiki/1939_Nazi_rally_at_Madison_Square_Garden).
NAFTA -- 1990s free-trade by Bill Clinton opened up Mexico and Canada as incredible trading partners. However, local industry / local steel lost out as companies started to shop in Mexico for material. As Bill Clinton was a huge pusher of NAFTA, the anti-NAFTA political group consolidated under Republicans. This is likely where the bulk of blue-collar workers is coming from, especially because Trump started adding Tariffs / anti-globalism concepts back to the forefront of American Politics.

Some more recent context:

Trump has been building his brand for decades as a very rich, very macho straight-talker. Even in the 80s and earlier, there's a large number of Hotels, Casinos, Resorts, Golf Courses (etc. etc.) that have relatively high reputation among Americans in general with Trump's name.
Trump reads from the teleprompter in "another voice", openly showing his disdain for public speaking and the political system. Anyone who has lost faith in the political system loves this. Trump pretends that the teleprompter is forcing him to talk and its all just a "through the motions" thing. Then Trump obviously goes off teleprompter and talks about different concepts, the "real stuff". (Or so goes his branding). This simple trick is enough to get the gist to his followers: don't listen to what I say (because I'm being forced to say this politically correct crap). This means that Trump's true actions are only limited to the imagination of the listener.
Trump is playing and leaning into the borne again Christian role. From a religious perspective, the "former enemy / former outsider" coming into religion is a common story and religious love it. Trump was openly a Democrat in the 90s / 00s before switching into Republicanism.

The "bulk" of Trump's political style is Know Nothing + Macho + anti-political correctness.

[–] sylver_dragon 5 points 2 months ago

I would add the admittance of China to the WTO as another proximate cause. And one which probably had more of a material effect than NAFTA; but, NAFTA had already become a GOP talking point and it just stuck. China's entry to the WTO was also moved over the finish line by Bush II, though most of the ground work was laid by Clinton. So, it wouldn't have had the same clean narrative as NAFTA. US Employment in manufacturing went into freefall in late 2000 and early 2001. This was also during a recession, so that is intermixed with the effects of those changes in international trade. But, even as the recession receded and the US entered an economic boom, leading up to the 2008 crash, manufacturing employment in the US either held steady or decreased slightly. It's unsurprising that the same period saw a lot of offshoring of manufacturing to China. And this was also the period of Neoliberal economists pushing "comparative advantage" and how the US losing all those manufacturing jobs was a good thing.

So it's not surprising then that they get bitter, they cling to guns or religion or antipathy to people who aren't like them or anti-immigrant sentiment or anti-trade sentiment as a way to explain their frustrations.
-- Barack Obama, 2008