what does in transit rb mean refers to a specific status update used by shipping carriers, particularly for packages being delivered through services like USPS. “In Transit RB” generally indicates that the package is moving through the transportation network and is on its way to the next destination facility. The “RB” part may be an internal code that refers to the type of transport or the facility where the package is currently located. Once the package reaches its final destination, further updates will indicate when it has been delivered.