Other that during World Wars, when has a majority of the population thought 'we're going in the right direction'? The 1800's when we were moving west, finishing off destroying the rest of the indigenous flora and fauna (including humans) that European settlers started in the 1500's? Perhaps the Native Americans and the African slaves might venture to disagree if anybody bothered to poll them.
How about post WWII and the wonderful burst of economic growth that comes after destroying a quarter of the planet? If you were black, poor white trash or pretty much anybody in the South you might take exception to the idea that the country was doing wonderful things. If you were white, lower middle class and / or a veteran, you had a 25 year burst of economic Good Times. That bubble got popped a while back.
If you were of the moneyed class at any time you did OK. Amazing how that seems to happen.
So don't go so much on 'polling' data. That is a fairly new, fairly narrow view of how the country is doing. Of course, trying to come up with a better way to figure out which direction we should be going is pretty much of a fool's errand. There are so many different aspects to life in this country (or any other) that the simplistic rose colored glasses / Red, White and Blue / USA! USA! metrics are perfectly useless.
Unless, of course, you are Donald who sees a giant group of disaffected people who are just waiting for some demagogue to lead them out of the swamp. His campaign has rolled on two correct assumptions. First, there IS a fairly homogeneous and large demographic that feels downtrodden and upset. Perfect fodder for his cannon. Second, the Republicans have, yet again, failed to create a candidate that isn't a complete cartoon. And they failed worse than the last two times which is pretty impressive. And sad.
With all of that said, all the Dems could do is pick Hillary. I understand it completely, she'll make a fine statist president and Murphy's Law (along with the laws of thermodynamics) will continue to be the driving forces in the Universe.
Murphy was an optimist.