Transferring between CO and Terminal A at IAH
 

My wife and kids will be arriving at IAH on CO tomorrow morning and will need to transfer to US, which flies out of terminal A. Is there really a bus that goes from B (or C) to A airside? How often does it run? Does the underground train still run? Any other options?

The IAH web site is no help and other threads say the map on co.com is out of date.

Yes, there is a bus that runs from B to the A terminal next to the COEX gates, but you can access the other A gates from there. The underground 1970's train still runs, its fairly quick, and neat to see how "futuristic" IAH was back in the 70's. The bus runs every 5-10 minutes, as does the train. Good Luck!