See the list of ballot STIDs here:

What is a Service Type ID (STID)?

The "Service Type ID" is a specific portion of the Intelligent Mail barcode (IMb), a special barcode used to track mail as it is traveling through the USPS system. Three digits long, the STID is the part of the barcode responsible for recording several things about an envelope: 

  • the class of mail (first class, marketing mail, etc.)
  • whether the sender would like address correction services, some of which are an additional cost (manual address, automatic address correction, etc.)
  • whether the sender wants to receive tracking data via Full-service or Basic Informed Visibility services. (Informed Visibility is the program that collects and transmits raw scan data to senders, formerly called Intelligent Mail Tracking.)

Why should I include these new STIDs in the IMbs on my ballot envelopes?

Using ballot-only STIDs differentiates your ballot envelopes from other types of mail within the USPS' internal tracking system. Prior to the introduction of ballot-only STIDs, nothing in the tracking data could tell the USPS the difference between a ballot and junk mail -  only the election mail logo, Tag 191s, and other physical markers could do that. If the postal workers handling the physical mail missed those visual cues or made a mistake with a batch of ballots, there was no way for USPS management to know that there was a problem until notified by election officials. Now, with the introduction of ballot-specific STIDs, the USPS can proactively monitor ballots that are traveling through the mailstream and analyze data about ballot delivery and delays. We strongly encourage use of these STIDs on all ballots mailed with Intelligent Mail barocdes for the November election.