For those of you who are not taking the SAT at a closed test center, you may have to deal with the possibility of not having your desired test center (or any test center) available as an option.
Although the test center shortage issue will probably be limited to the October and November test dates only, here's what you need to do if you find a similar issue when you register for the December and January test dates.
To register, visit the College Board website:
Note that you will not know whether a test center is available until midway through the registration process.
If you are denied a test center while going through the registration process, you should opt for the "Let College Board find a Test Center" option per the screen-shots detailed here. Students going for the October and November test dates were assigned a place on an ad hoc basis this way:
NOTE: You will not have this option if you have already registered for another test date and want to change test dates! You will need to contact College Board directly by phone during College Board's office hours from 8 AM - 9 PM EST (12 hours behind Singapore Standard Time). You will also have to pay a fee to change the registration date.