We understand that it is disappointing and frustrating for a customer when he experiences the USPS tracking info not updating. But at times, even the most efficient service may fall prey to some glitches. Hence, we suggest you keep calm as your package will inevitably arrive in few days. You can also visit your local post office or call 1-800-ASK-USPS® (1-800-275-8777) for further assistance.
We are sending all packages via USPS. USPS has a lot of storage and fills gaps in passenger flights with packages when going to different US region sorting centers, which causes a bottleneck (During Christmas last year with the compounding weather issues, we were seeing delays of up to 2 weeks). Its been about 3 years now and the delays are 4/10 on packages going through there and mostly around heavy travel holidays due to less available transit space.
Our suggestions is to contact local USPS office and try find out why the package is delayed.