Re transports and health requirements for transport:
I personally prefer the paid transports b/c they seem less stressful to the dogs, they are less risky (dogs have been lost in volunteer transports). In the volunteer transports, the dogs have to switch drivers and vehicles every hour, with the drivers being handlers of varying skills. In terms of cost, the paid transports seem more efficient. If every volunteer driver would donate their gas money to the rescue, the rescue could pay the paid transport and then some. But people disagree on that, and some rescue organizations do well by bringing the dogs up with volunteer drivers.
The good paid transporters require that the dogs have been out of the shelters for at least 2 weeks prior to transport to reduce the risk of disease. They also need a health certificate, need to be s/n, fully vaccinated, and parasite free.
This means, the shelter in the South needs foster homes where the dogs can stay for at least two weeks. Or have enough funds to board at a vet's or a boarding kennel with good sanitary practices.
* As others mentioned, Rescue Road Trips drives from LA via VA to the Northeast: http://www.rescueroadtrips.com/Schedule_%26_Rates.html
I am not aware of a paid transport going from LA to MI or WI, but that is not my area, so I don't know.
The volunteer pilots of PilotNPaws fly with small airplanes that typically have a reach of about 300 miles, so longer trips have to be done in legs. I flew on one such leg as a handler and the aircraft was too small for a 36x24 crate to fit in, we had to put the dog on the rear bench. Other planes are larger and can fit two large crates. Last I checked, PNP did not have health requirements, it's up to the individual pilots whom they want to fly, just like volunteer ground transport.
More to come