Originally Posted by chgoeditor

Oh, you reminded me of another point I'd forgotten to make: For airports like Hong Kong's, a city air terminal makes sense because the vast majority of passengers are coming from Point A (Kowloon/Hong Kong Island) to Point B (the airport). And those that aren't coming from downtown are still approaching from the same direction.

But where would the OP locate an offsite center in more sprawling metropolitan areas where people approach the airport from many directions? I live about six miles north of downtown Chicago. I am NOT going downtown to check in for a flight at O'Hare. But nor am I going to drive past ORD to an offsite center in Arlington Heights or Schaumburg. My mother lives in central New Jersey. If she's flying out of EWR, she is not going to Manhattan or even Jersey City to check in for her flight. In a densely populated area, the notion of driving in the opposite direction from the airport or past the airport to check in/clear security is a ludicrous idea.