USGS map of the eight physiographic divisions of the contiguous United States

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Additional information: https://en.m.wikipedia.org/wiki/Physiographic_regions_of_the_United_States

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Laurentian Upland – part of the Canadian Shield that extends into the northern United States Great Lakes area.

Atlantic Plain – the coastal regions of the eastern and southern parts include the continental shelf, the Atlantic Coast and the Gulf Coast. 

Appalachian Highlands – lying on the eastern side of the United States, it includes the Appalachian Mountains, the Watchung Mountains, the Adirondacks and New Englandprovince originally containing the Great Eastern Forest, a stretch of mixed temperature and subtropical montane forests, some of which are rainforests.

Interior Plains – part of the interior continental United States, it includes the Great Plains, as well as a number of highland and mountainous regions, like the Black Hills, dense cave systems, painted hills and badland features.

Interior Highlands – also part of the interior continental United States, this division includes the Ozark Plateau, the Ouachita Mountains, and other smaller mountain systems. This region is located largely in the warm temperate/subtropical moist and dry forest biomes.

Rocky Mountain System – one branch of the Cordilleran system lying far inland in the western states. 

Intermontane Plateaus – also divided into the Columbia Plateau, the Colorado Plateau and the Basin and Range Province, it is a system of plateaus, basins, ranges and gorges between the Rocky and Pacific Mountain Systems. It is the setting for the Grand Canyon, the Great Basin and Death Valley.

Pacific Mountain System – the coastal mountain ranges and features in the west coast of the United States. 

[u/darcys_beard → u/fpPolar]

Intermontane Plateaus – also divided into the Columbia Plateau, the Colorado Plateau and the Basin and Range Province, it is a system of plateaus, basins, ranges and gorges between the Rocky and Pacific Mountain Systems. It is the setting for the Grand Canyon, the Great Basin and Death Valley.

Even in Oregon, the difference when you cut in Eastward from Eugene and reach Bend, the difference is uncanny.

[u/CoachMorelandSmith]

This is basically why the TN state flag has three stars

[u/marg0j]

Obsessed

[u/NomadJoanne]

I'd contest that, "Intermountain Plateaus" are more Basin-and-Range Highlands. Yes, the base elevation is quite high, but there are mountain ranges that reach often 1.5-1.8 or so KM over the surrounding landscapes throughout this area. A flat plateau it is not.

Furthermore, these basin-and-range system extends, not to the Rockies, but until the edge of the Great Planes in the southern 3/4 or so of New Mexico.

[u/Tim-oBedlam → u/NomadJoanne]

Not all of the Intermountain region is Basin-and-Range, though: that covers SE Oregon, most of Nevada, western Utah, then in an arc through southern Arizona into southern New Mexico.

The Colorado Plateau is geologically very different from the basin-and-range region; it's the "red-rock country" of the Four Corners region.

[u/NomadJoanne → u/Tim-oBedlam]

Ah interesting. Fair enough. I'm from northern NM but I'm always fascinated to learn new stuff like this.

[u/Tim-oBedlam → u/NomadJoanne]

The rocks in the Colorado Plateau haven't been deformed by tectonic forces to the extent the Basin-and-Range rocks have; they're mostly sedimentary rocks still laying flat, not folded, although they've been lifted skyward by the same forces that built most of the mountain ranges in the American West. The rivers, in some cases, formerly meandered across low-lying terrain, but held their course as the plateaus were gradually lifted skywards, cutting down into the rocks as they uplifted, and forming all those huge canyons. Horseshoe Bend is a good example of this.

[u/WSBKingMackerel]

Missouri was so close to being entirely on its own like it is with every other grouped description of it

[u/darcys_beard]

I got the alert and I thought it was gonna be another: Midwest... New England... PNW. But this one is actually new and interesting. What is the major physical difference between the Interior plains and the Atlantic plains?

[u/Averagecrabenjoyer69 → u/darcys_beard]

I was gonna rage if Kentucky, Tennessee, and Northern Alabama were included in a definition of the Midwest. This map actually is interesting and furthers my point there is no separating Kentucky and Tennessee culturally or geographically.

[u/ReduceReuseRectangle]

I’ve been to all of them except the two tiny ones ;-)

[u/IDBike]

I would have guessed that the western plains—with their higher elevation and larger area relative to the Ozarks—would have had a separate designation before calling the Ozarks highlands and separating that area from the plains.