We have tags for many U.S. states and cities, and usa for the whole country. But then we have
- western-usa (11 questions) for the continental US west of the Mississippi River
- eastern-usa (11 questions) for a currently undefined area
These aren't regions, but simply divisions, and I would argue that neither is useful as currently implemented. These are huge swaths of land— so huge that the differences between them are slight. To the extent that Rhode Island and Mississippi have something in common, they have an equal chance of having them in common with Missouri or Nevada. To the extent that Illinois and Arkansas are different, there's an equal chance that they're just as different from Connecticut or Washington State. We don't benefit the visitor by grouping such vast collections of disparate areas together.
Since neither tag is heavily used— not only are there only 22 questions between the two of them, but a large proportion of the questions within them are closed— I would simply retag these questions as usa. Or, we could retain western-usa but redefine it as a region, rather than a division, moving the boundary line to the Rocky Mountains instead of the Mississippi River and adding northeastern-usa, southern-usa, and midwestern-usa as its counterparts.
The main trick with the latter option is that except for new-england, the definitions of U.S. regions are always somewhat disputed. Historically, for instance, the South began at the Mason-Dixon Line separating Maryland and Pennsylvania, but nowadays you'll find sources that group Virginia, home of Robert E. Lee, in the Northeast. If we can agree to use the U.S. Census Bureau definitions for the four super-regions and enforce it, though, at least we have a standard to adhere to.