Do Louisiana and Arkansas belong in the western South or South Central region?

[King of Kensington]

The Census Bureau puts them in the West South Central division with Texas and Oklahoma. 

[Born to Slay. Forced to Work.]

The census’s definition of the south is notoriously controversial. But yes they are the western edge of the south.

[Del Tachi]

If you had to split the states up into regions, I suppose this would be the best way:

New England - CT, MA, ME, NH, RI, VT
Mid-Atlantic - DE, MD, PA, NJ, NY,
Appalachia - AR, KY, TN, WV
Southeast - FL, GA,NC, SC, VA
Deep South - AL, MS, LA
Great Lakes - IL, IN, MI, OH, WI
Great Plains - IA, KS, MN, MO, NE, ND, SD
Southwest - AZ, NM, TX, OK
Mountain - CO, ID, MT, UT, WY
Pacific - AK, CA, HI, NV, OR, WA

The placement of Oklahoma is rather unfortunate. 

[King of Kensington]

I feel that Texas and Oklahoma should be together for sure.  Both are south with a western bent and both have demographics that are more typical of the western half of the country (Mexican in Texas, Native American in Oklahoma).

From what I understand during the Great Migration Blacks from Louisiana and Arkansas went mostly
westward to California rather than north, like those in Texas and Oklahoma.

[Oryxslayer]

From what I understand during the Great Migration Blacks from Louisiana and Arkansas went mostly
westward to California rather than north, like those in Texas and Oklahoma.

Yes, this is true, and it speaks to the wider point of discussion. While there are similar cultural trends occurring in say Arkansas and Tennessee, the Mississippi River is a delineator for many more patterns of human behavior both historically and presently. So for the census's semi-arbitrary delineations, the region works.

Texas is always hard to decide whether it goes in the south or west, and that'll just effect every surrounding grouping.

[King of Kensington]

Most common states of birth for Southern-born Blacks, 1970:

Detroit  Alabama (135,500), Georgia (92,500)
Chicago  Mississippi (372,100), Tennessee (85,900)
St. Louis  Mississippi (110,000), Arkansas (47,800)
Los Angeles  Texas (161,500), Louisiana (147,000)

https://lawrencemigration.phillipscollection.org/culture/migration-map

[King of Kensington]

Yes, this is true, and it speaks to the wider point of discussion. While there are similar cultural trends occurring in say Arkansas and Tennessee the Mississippi River is a delineator for many more patterns of human behavior both historically and presently. So for the census's semi-arbitrary deliniations, the region works.

Texas is always hard to decide whether it goes in the south or west, and that'll just effect every surrounding grouping.

Arkansas has pretty typical Southern demographics, Louisiana is a big demographic outlier with Franco-American South Louisiana and the Irish-Italian presence in New Orleans for example).   Neither have a western identity or orientation, yet Louisiana does resemble East Texas in some ways. Obviously culture does not neatly follow state lines.