No level of government has official designations for regions. The U.S. Board on Geographic Names, which is responsible by law for standardizing geographic name usage throughout the Federal government, is often asked for official names and boundaries of regions, but does not and cannot provide them.
Regions are application-driven and highly susceptible to perception. Individuals might agree on the core of a region, but agreement deteriorates rapidly outward from that core. The criteria or application would have to be defined, such as physiographic (this would include parts of States, but there is more than one system); political (definite disagreement based upon perception); cultural (unlimited variables); and other applications.
Regional definitions applied by any organization reflect their particular needs or application, not a government standard.