Answered by ZUPAN | Oct. 25, 2019 13:44
Sue, if your itinerary is:
US - Hong Kong - Shanghai - Hong Kong - US
Then you are not eligible for any kind of visa free transit scheme because you are not in transit. You depart from Hong Kong to Shanghai and also return to Hong Kong. This is not allowed and if you want to retain this itinerary, you will need a Chinese visa obtained in advance.
Instead of the mentioned itinerary, I advise you to use Macau and to construct your itinerary like this:
US - Hong Kong - Shanghai - Macau - Hong Kong - US
Macau and Hong Kong are so close to each other and you can easily return to Hong Kong after you have returned to Macau from Shanghai. Also, by relying on this itinerary you will be eligible for 144 hour visa free transit in Shanghai area.