That is not necessarily true. Look at this for example that was shipped from Shanghai.
Destination country - United States
CHESAPEAKE, VA 23324, Delivered, In/At Mailbox, Your item was delivered in or at the mailbox at 12:40 pm on November 13, 2017 in CHESAPEAKE, VA 23324.
CHESAPEAKE, VA 23324, Out for Delivery
CHESAPEAKE, VA 23324, Sorting Complete
CHESAPEAKE, VA 23324, Arrived at Unit
NORFOLK VA DISTRIBUTION CENTER, Departed USPS Regional Facility
On its way to CHESAPEAKE, VA 23324, In Transit to Destination
NORFOLK VA DISTRIBUTION CENTER, Arrived at USPS Regional Facility
HYATTSVILLE, MD 20785, Departed USPS Facility
HYATTSVILLE, MD 20785, Arrived at USPS Facility
STAMFORD CT DISTRIBUTION CENTER, Departed USPS Regional Facility
STAMFORD CT DISTRIBUTION CENTER, Arrived at USPS Regional Facility
ISC NEW YORK NY(USPS), Processed Through Facility
Origin Post is Preparing Shipment
CHINA, SHANGHAI EMS, Processed Through Facility
Origin country - China
Arrive at the delivery office
Shanghai, leaving Shanghai to Shanghai Pudong Terminal
Shanghai, leaving Shanghai to New York Kennedy Airport
Liquan Road, Shanghai, China (name of the collector: Zhu Lei, Tel:)
I am still waiting on a package that's supposedly shipped to JFK from Shenzhen a day after this package on 11/2/17 It's now been 4 days later then the example listed above. And it still has not cleared through customs (assuming that it's even in the United States)
I truly believe the problem is on China's side especially from the Guangzhou and Shenzhen areas. Packages arriving from or being shipped through Shanghai seem to be fine.They seem to be having some sort of issue. Personally I still think packages are still sitting in China, because the packages that are making it to the United States are clearing customs in less than a week.