I was right. This is from Delta's website
As you see there is a walkway from B to C to D, and to E. that box thing where E and D come together is where customs are, those are used for the Mexico flights. Concourse E is Skywest.
Concourse D is Delta
Concourse C is Delta
Concourse B is Delta plus all the other airlines, the second part of B (lower level) is all Southwest.
Gates A (not shown) are for Sunrise Airlines (don't know if they still operate)