According to the recent episode of BackStory, John Wesley Powell (leader of the US Geological Survey from 1881 to 1894) suggested to Congress that the key organizing principle of the western states should be drainage areas. He recognized the likelihood that water would be too scarce to meet all the development desires and thought this sort of organization would allow communities that share a resource to work toward common political solutions.
If his districts have been used, we'd be in that green blob on the left, instead of California. (You can click it to get a bigger view.)
Personally, I'd propose that our state be called Nevada, because the other one wouldn't exist. Then we wouldn't get asked that question all the dang time. Alternatively, we could call it Lahontan.
What would you call our water-based state?