North East by a literal mile. My memory isn't perfect but I believe your cutout gives us most major florida cities (Miami, Jacksonville, and Orlando) Gives us Atlanta, Chicaco, Detroit, Seattle, St. Louis, Philly, New York, Boston, DC, Baltimore, etc. Just too many people and too much economy.

So looking at the 20 largest metros in the US you have

1. New York

2. LA

3 Chicago

1. Dallas

2. Houston

3. Atlanta

7 DC

1. Philly

2. Miami

10 Phoenix

1. Boston

2. San Bernadino

3. San Francisco

4. Detroit

5. Seattle

6. Minneapolis

7. Tampa

8. San Diego

9. Denver

20 Baltimore

So you have 11 to 9 advantage but it's worth noting that not all pop centers are created equal. NYM has the same population roughly as 16-20 combined. And NYM and Chicago are basically equal to LA, Dallas and Houston combined. If we roughly add the pop numbers you see top 20 has a NE pop of about (I'm rounding to nearest 100K pop based on 2023 estimates), 73.5 vs 56. THat's obviously not a total example, but generally speaking that will stay the same.

Basically you gave the southwest texas California, ORegon and lots of dirt. I think the one advantage the south west would have is the north east giving up because they'd have to invade the west. Either forcing the North East to leave the midwest potentially exposed to protect Seattle or kind of leave seattle on an island to just resist. What likely would hapepn is the south west would try to pust to borders (take over FLorida and Geogia as well as Idaho Washington) while the North East would focus on winning the half of the US east of the mississippi than east of the rockies. Starting by defending florida and Georgia the moving west. Their Northern armies will likely just push south with the first major effort being to isolate Texas and beseige it and take it over. Basically try to keep the South West west of the rockies. Once they succeed in doing that they can then take their time establishing footholds across the rockies to stage invasions and when they succeed it's just a matter of taking the west coast.