Singapore ---> Shanghai ----> Los Angeles

Hello,

My wife and I will be traveling from Singapore to Shanghai and then onward to Los Angeles. Understand that this should qualify for either the 72 or 144 hour free transit is that correct (we are US nationals)?

However, note that we have lived in Shanghai for 2 years and in the course of our travels our current visas will expire. Not sure if this changes the answer to the above???

Thanks in advance for your help, it is greatly appreciated!
Kind Regards,
Andrew