In transit may be the term for being shipped to your local delivery facility, seems like there's another status for when it's in the local delivery route truck. Just give it another day.
Don't rely too heavily on the USPS tracking website. Their "delivery date" is usually just an estimate.
USPS is very unreliable, and even when you buy guaranteed delivery postage, it's not guaranteed. There's nothign you can do besides reporting it to the post master
"in transit" means that the pkg is on it's way to your local PO; when it's ready to be delivered, you should have a tracking msg "out for delivery" or similar
What you should do is have patience. The date of delivery they give is an ESTIMATE, not a guarantee. It is Christmas season and mail is super busy.
If it never comes, contact the sender.
The mailman kept it.
