Just wondering if there is a bus route that goes to Marigot across the causeway from the airport?

I personally have not seen a bus at the airport.

The busses are actually private jitneys that hold about 12 people. While they basically run what might be called a route, there's no schedule. Route is posted on the bus windscreen. People flag them down when needed.

If you're not renting a car there will be cabs available or you can book a driver such as Mr. Brooks, a sponsor at this website. Look under the sponsor list.

There is a bus stop right outside the airport on the road (going both directions). We never took a bus to Marigot but I did see buses with the sign for Marigot in the front window.

Thanks that sounds promising. Previously we had to get on the bus to Phillipsburg, and get on another bus to Marigot somewhere along the way.
George