Originally Posted by npei

Welcome to FT.
Please clarify if you are flying AA or Delta or UA.
It is widely understood that AA or Delta will give lots of grief trying to get boarding pass for LAX-PVG on TWOV [e.g. you may not succeed because agents lack training].
UA is slightly better experience because some agents have experience with TWOV while others dont', so you need to have hard-copy printout of TIMATIC rules[listed in wiki] and hotel rsv and onward ticket confirmation info