货件里的追踪编码是由货代提供。
2货代在收到你的货的时候就会通过他们自己的物流后台向国外USPS/UPS等的代理号申请 追踪编码(那时候就有追踪码了),等货从中国飞到美国海关,当地UPS收到你的货后再换卡车/快递配送。(如果中途物流那边出问题,会有更换追踪码的情况)
希望我的回答对您有所帮助。
The tracking code in the shipment is provided by the freight forwarder.
2 When the freight forwarder receives your shipment, they will apply for the tracking code from the USPS/UPS agent number abroad through their own logistics background (the tracking code will be available at that time), and wait for the shipment to fly from China to the US customs. After the local UPS receives your shipment, it will change the truck/express delivery. (If there is a problem with the logistics in the middle, the tracking code will be changed)
I hope my answer is helpful to you.