One major problem with regional names is, officially the state border lines encompass many different regions within the states that may match up with a neighboring region in a different state better, but for official purposes it's easier to just include a whole state in X region. New England was lucky being defined so early and having very clear natural boundaries that its entire cultural region could be squeezed into. For example, Alabama is primarily a Deep Southern state, but its northern third or so is very Appalachian-feel-and-settled and would've been in the proposed state of "Nickajack".
OTL (or at least OTL-ish) names, maybe jiggled a bit here and there to take in a neighboring area culturally identical in daily life:
-The Deep South has Dixie(land), that is, states primarily settled by South Carolinian aristocratic planters, their poor white workers, and black slaves (South Carolina west to Louisiana).
-Virginia, Maryland, and North Carolina can be lumped together as the Chesapeake. This area was primarily settled by noble second sons fleeing the English Civil War, poor white workers, and slaves, but never matched Dixieland in extremity.
-As mentioned, Cascadia is common for Washington, Oregon, and with Idaho lumped in for a natural border at the continental divide. Liberal, environmentally friendly, etc.
-Northwood(s) could take in Minnesota, Wisconsin, and the UP of Michigan (IE, the "Upper Midwest"). It was settled by Yankees, followed by a semi-small batch of Catholic Germans and a larger batch of Protestant Scandinavians (who the Yankees liked better). This area is where the "Minnesota/North-Central" accent resides.
-I've always thought Heartland could shift to encompass first and foremost all the Great Plains states (Dakotas, Nebraska, Kansas, Oklahoma, Colorado, Wyoming, perhaps Iowa).
-Aztlan could take in New Mexico, Arizona, and the Trans-Pecos area of Texas, although this is used by the Chicano Reconquistia group and so may be controversial. This is the most Hispanic-settled area of the USA.
-West Virginia, Kentucky, Tennessee (barring its western third that's Dixie in feel, but it's being lumped in), and the mountainous southwestern/pure-western/northwestern parts of Virginia-to-Alabama can defined as Appalachia, settled by northern English and the Scots-Irish. Notice the mountainous parts of Virginia-to-Alabama may be lost and lumped into Dixieland if you're going by whole states being in a region together, despite being settled by Appalachian-men and not Dixie-men.
-Hilariously, California and Texas on their own are singular states big enough to serve as their OWN cultural areas with sub-cultures/areas within them (notice NorCal and SoCal are technically different but each would probably fit in quite well into a layman's thoughts on California). Local nationalism a la Cascadia, New England, "the South", etc. plays a part in this definition.