The conservative philosophy can basically be summed up as, "Hey, we were absolutely AMAZING in the 1950s. Let's keep it that way- any change is necessarily for the worse."
Whereas liberals say, "Let's try to make things better."
Since the latter requires accepting that America is, and never was, perfect, obviously that's how the polls will skew.
Conservatives love America like a 4 year-old love his mommy. Unconditionally, unthinkingly, and anyone who criticizes or is mean to her is just a big meanie.