Baltimore is a city port. Goods aren’t necessarily destined for Maryland.
Baltimore is one of the largest bulk ports on the east coast. They also have large inside storage warehouses that other ports do not have.
The other favorable thing about Baltimore is that the trucking freight out of that port is pretty reasonable in comparison to other east coast ports.
Meaning, you pay a lot less per mile on the trucking out of Baltimore as oppose to Newark, Philly, Wilmington, New Haven, Charleston or Savannah.