Why do Americans seem to dislike liberals? Did we forget how much liberals contributed to American society?

[Gamer]

I am not a liberal myself. I am a moderate conservative.

Liberals:
founded the country (the conservatives were pro-British)
built the American government (a federal three-branch government was a novel idea that was never put into practice until the framers came along)
ended slavery (the conservatives were pro-slavery)
established labor unions (the conservatives were venture capitalists who only served themselves with ruthless business tactics)
articulated the idea of socialism (underscored the importance of government regulation of industry)
helped us out of the Great Depression (FDR exercised unheard-of levels of peak government control of industry with Social Security, market watches, public works investments to create jobs, etc.)
invented welfare (LBJ's Great Society cut poverty in half in four years)

Note that I do not agree with everything that liberals say. I disagree with some points about animal rights, gay rights, etc. I am a moderate conservative.

In all of this, please remember to answer the main question.
I'd like to thank DirkPotters for pointing out something that I wrote: when I said FDR "helped us out of the Great Depression," I should have been more clear in saying that his applied socialism prevented the worst of the Great Depression and sustained America long enough for economic growth from WWII to kick in.