Entering China twice

I apologize, but your question is a bit unclear. I assume that you are US citizen and this make you eligible for 144 hours visa free transit. Anyway, you have just informed us that you plan to travel from Denver to Shanghai and that you plan to stay in Shanghai for 144 hours TWOV.

Please, would you be so kind and just clarify how will you travel from Denver to Shanghai because there are no direct flight connections between the two cities and where do you plan to travel after you have visited Shanghai. I don't ask out of curiosity because these are necessary factors to be able to give you a reliable answer.

Also, you have mentioned in your title "Entering China twice"... This is also not a problem if the flights are tuned in right order.

So, just add a few more details and you will receive an answer within the couple of hours or even faster :).

I apologize, I thought I put more info into my original post but somehow I must have deleted the info. We are flying Denver to Shanghai with a layover in SFO. Once we arrive in Shanghai we will be there <24 hours before we fly to Japan. We will be in Japan for about 2 weeks then fly back to Shanghai where we will be for 4 days before we leave back to Denver.

Well, we have:

Denver - San Francisco - Shanghai - Japan
Japan - Shanghai - (certain layover in some place) - Denver

This is fine and allows you to apply for 144 hours visa free twice or you can apply for 24 hours visa free during your first stay in Shanghai if you will be there less than 24 hours. Please, just take all the necessary documentation, i.e. flight tickets and hotel bookings in Shanghai in printed form.

In the end, please, just be informed that your flight from Shanghai to Denver is allowed to have a layover, but not in Japan. I assume that it will be a layover again in US and if I am right, then everything is just fine.