No State Lies in Arkansas' Southwest Corner—Texas Borders It

Geography Clarified

The question contains a premise error: no state is located *inside* the southwest corner of Arkansas. States border other states; they don't nest inside corners.

The Actual Neighbor

The state directly southwest of Arkansas is Texas.

• Arkansas's Southern Border: Louisiana (mostly).
• Arkansas's Western Border: Oklahoma (north), Texas (south).
• The SW Corner: The tri-point where Arkansas, Texas, and Louisiana meet is near the town of Doddridge, AR / Atlanta, TX / Rodessa, LA.

Arkansas's Six Neighbors

1. Missouri (North)
2. Tennessee (NE - Mississippi River)
3. Mississippi (East - Mississippi River)
4. Louisiana (South)
5. Texas (SW)
6. Oklahoma (West)

So if you're standing in Texarkana (AR/TX border), looking southwest—you're looking into Texas.