Always point of entry, and yes, 1.5 hours is cutting it very thin. I usually try to schedule a 3 hour layover if I have to fly through the US (which I avoid if I can). Try to get seats in the front of the cabin and let the flight attendants know. They may usher you out in front of everyone else and then run like hell and hope for the best and that no other international flight arrives at the same time.
Also, it's not just immigration you have to worry about. You will also have to pick up your bags and go through customs. Coming from SA this might take a while, especially if you fit the profile, if you know what I mean. On the bright side, there is usually a baggage drop off just outside customs. You just put it on the conveyor belt.
You will also have to go through another security screening before you get to your gate. Even if you make it, your bags may not. If I were you, I would try to change the flights. I have done it in 1.5 hours in LAX a few times, but my bags didn't.
I assume you will be entering under the Visa Waiver program, in which case you must get pre-approval by applying online at https://esta.cbp.dhs.gov/esta/
. It'll cost you 14 bucks, but it's good for 2 years. This replaces the form you used to have to fill out on the plane.
Last edited by boarder; 16 May 2012 at 19:10.