The current drought in the southern US offers a perfect example of the tensions between state and national interests. When times were good, the states benefited tremendously from the heavily subsidized, totally bureaucratic US Army Corps of Engineers. This is another one of those activist things set up in the 1930's, that can never die.
Those busy army beavers set up a national system of water flow and dams, to increase general regional wealth. And it worked at the time. Now, states such as Georgia want to ditch all that, and keep all the water stored in their state. To heck with those people downstream!