An update:

according to Tom Bossert, U.S. Homeland Security Advisor to the President, at a White House Press Conference this afternoon, said (and I am paraphrasing here, not quoting exactly):

The U.S. Dept. of State and Dept. of Defense are (jointly) in the final stages of planning to implement evacuation of U.S. citizens from St. Maarten / St. Martin.

My comments:
They are aware of Hurricane Jose, and that is complicating any implementation of their plans. We should hopefully know more from the govt. tomorrow.

In their planning, he mentioned they are estimating there is somewhere between 350 to 6,000 U.S. citizens to be evacuated!
(Therefore they are clueless to an actual number.)

Therefore I think it is important for them to know who (in terms of U.S. citizens are on island), so they can send adequate assistance (planes) for evacuation. I assume most U.S. citizens would like to get off of the island and back to the U.S. in the next week or so!

That is why I think it so important for U.S. citizens "register" or contact them as described above.

A Family member at home can do it on their behalf!
Go to the links above.

And I agree that this thread should be pinned to the top