Mindless partisanship

The thought strikes me that when the Democrats took power in 1932, they went on to win WWII, end the Depression, lay the groundwork for winning the Cold War, and firmly establish the principle of equal rights for all, regardless of skin color or gender. When the Republicans took power, they embroiled the country in a disastrous war, took a nasty shit on the constitution, and destroyed the economy. In about 1/12 the time the Democrats had. It's so ridiculous that my reflexive instinct is to say it's all absurd, that I'm being some kind of mindless partisan. But I keep trying to think my way around it, and I really can't. I can point to instances of bad times under the Democrats, of a blunder here, an excess there, but overall, the period between 1932 - 2000 was the best 70 years in the history of this country. It was one long stretch of growing prosperity, prestige, power, influence, respect, and freedom. To go from that to where we are now -- how is that possible?