Average balance of power of all three branches.

[Brian37]

Correlation =/= causation.

While I agree that 'Reaganomics' and deregulation has been a long-term disaster, the graph you reference really doesn't make a strong case that the Democrats, while in power in Congress, were necessarily anything other than the political beneficiaries of a sudden boom in production during the war years, followed by a nearly unprecedented period during which the U.S.'s only serious European and Eastern Asian economic competitors were struggling to put their shattered economies and societies back together after the war, from which America had emerged nearly unscathed.

But if the Democrats are to reap the praise for the economy during the '50s and '60s, is it also the case that they are to blame for the stagnating economy of the '70s? I would argue that the reasons for that decline -- like the reasons for the successes of the previous two decades -- had much to do with developments overseas, in this case the oil embargo, and cannot be tied in a simple one-to-one, cause-and-effect relationship to specific economic policies the party adopted.

ARE YOU SAYING THE REPUBLICAN ECONOMIC POLICIES ARE GOOD THINGS?!?!?

Not right now no. The parties flipped over time.