What Do USPS Tracking Numbers Start With For Different Shipping Options

When sending a package through USPS, one thing to look forward to is the tracking number for the package. These numbers help you track packages until they arrive at their final destinations. What do these identifiers start with? 

USPS tracking numbers are typically a combination of letters and numbers, which can be 13 to 22 characters long, depending on the mailing service. This guide explains the different USPS shipping options and what their tracking numbers start with. 

What Do USPS Tracking Numbers Start With? 


USPS tracking numbers are usually a mixture of numbers and letters. However, some feature only numbers. Here is a breakdown of what works for different shipping options: 

1. EA 

USPS tracking numbers that begin with the prefix “EA” are sent through Priority Mail Express service (the fastest domestic service). This service guarantees overnight delivery to most domestic locations with a tracking number like EA 000 000 000 US. 

2. CP 

“CP” is the most common USPS tracking number prefix. It features in packages under First-Class Mail, Priority Mail, and other USPS services. An example of such tracking numbers is CP 000 000 000 US. 

3. CJ

The prefix “CJ” begins the tracking number of an international shipment, using the Customs Declaration Form. An example of such tracking numbers is CJ 000 000 000 US. 

4. RA

USPS tracking numbers that begin with “RA” represent packages sent through the Registered Mail service. Registered Mail is the most secure USPS service because it provides complete insurance coverage and requires a direct signature upon delivery. 

The tracking number for packages under this service should look like RA 000 000 000 US. 

5. LK 

“LK” is used for packages sent via the Library Mail Service. This service is used for circulating books and other materials between libraries and other book-related organizations. 

However, such packages must meet specific size and weight specifications. Their tracking numbers should look like LK 000 000 000 US. 

6. LJ or LP

Tracking numbers that begin with the “LJ or LP” also represent packages sent via Library Mail Service. However, this service differs from “LK” packages because it uses Media Mail service to ship (which is usually more cost-effective).

The tracking number for packages under this service should look like LJ 000 000 000 US or LP 000 000 000 US. 

7. LC 

The prefix “LC” is used when sending a package through letters that have a customs declaration form. This service is a combination of USPS mail service and customs declaration. 

An example of tracking numbers that begin with “LC”  is LC 000 000 000 US. 

8. LX 

When the tracking number for a package begins with “LX”, it means it is sent via the USPS “Legally Controlled Mail” service. Government agencies mostly use this service to send and receive documents. 

An example of such tracking numbers is LX 000 000 000 US. 

9. 94

Tracking numbers that start with “94” mostly belong to packages under Priority Mail. Such tracking numbers are usually 20 to 22 characters (numbers only) long. An example of such a tracking number is 9400 1000 0000 0000 0000 00.


How much is USPS tracking?

Free tracking generally accompanies Express Mail, Priority Mail, or Standard Post service when you purchase postage at the post office. Otherwise, you have to pay. 

How long are USPS tracking numbers valid?

It depends on the type of parcel. A parcel that does not require a signature upon delivery often features tracking numbers that last 120 days, while signature parcels can be valid for 2 years. 

How can you tell if a USPS tracking number is real?

The simplest way to confirm the authenticity of a tracking number is to enter it into the USPS tracking portal. If it does not pull up any result or order information, such a code may be fake. 


USPS tracking numbers start with different numbers or letters depending on the type of package and service you choose. While most USPS tracking numbers will feature a combination of letters and numbers, some contain only numbers. 

For mailing services with tracking numbers that start with letters, those letters often appear first, as seen in the examples above. On the other hand, if the tracking number begins with a number, there is a likelihood it will contain only numbers. 

I hope you found this guide helpful. If you did, please see how to track USPS packages without tracking numbers

Thanks for reading.