Why does USPS show "Item in transit to destination"?This event appears on items that have not had an actual device scan them in 18 hours. This means that the item is possibly still in the plane, train or truck. It also can mean many other things.
In most cases, the package will had an device scan within 18 hours. But sometimes if the barcode of package get damaged in transit, the package will go dark for a while, it doesn't mean your package has been stolen, destroyed in transit, it can simply mean it got stuck at a facility.
If usps have a truck break down on the way because of bad weather, it may delay the mail almost ten hours. And the "in transit" event may show on the tracking results.
What can I do if USPS shows "in transit"?You can call your local post office, and they will just give you some platitudes to try and console you. Actually there is nothing they can do or they are just too busy to care. Except your parcel is Express (usps will refund money if not delivered on time) or domestic registered mail (usps will pay up to $5000 if lost). The local supervisor is only concerned with how quickly item are scanned arrived at his post office. They do not really care about individual parcel that have not yet arrived at his office.
So the fact is, you can just wait for new updates, and the congestion theory is the most likely reasons. You can track USPS package everyday to see the latest updates.