Inside Look at USPS Sorting Facilities: How Your Mail Gets Processed

Have you ever wondered what happens after you drop a letter or package in the mailbox? How does the U.S. Postal Service manage to process and deliver an average of 425.3 million mail pieces each day? The magic happens at USPS sorting facilities located across the country.

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These massive processing plants are the first stop for your outgoing mail and the last stop before mail carriers bring letters and packages to your door. Sorting facilities are like the central nervous system of the U.S. mail—hubs that connect every address in the country.

Let‘s take a behind-the-scenes look at what happens at these facilities and what it means when you see "departed USPS sorting facility" on your tracking information. As a retail and consumer expert, I‘ll share some insights on how these facilities impact businesses and customers.

What Are USPS Sorting Facilities?

The Postal Service has a network of over 350 processing and distribution facilities spread out across the U.S. These plants take in mail collected from blue collection boxes, post offices, and large-volume shippers, then sort and route the mail pieces for transportation to the next facility along the delivery path.

Sorting facilities range in size from 50,000 to 500,000 square feet. The largest is the Chicago Metro Surface Hub, a 24/7 operation that spans 14 acres and can process over 3 million packages per day.

Facilities are strategically located to cover every part of the country and enable an efficient flow of mail. Major cities usually have at least one sorting plant, with especially high-volume areas having multiple facilities. Suburban and rural regions are covered by facilities in the nearest city.

All classes of mail, from postcards to Priority Mail packages, pass through sorting facilities. The only exception is Express Mail, which is segrated and transported separately to meet the overnight delivery timeframe.

According to USPS data, the average sorting facility processes 1.2 million mail pieces per day, with the top 10 facilities averaging over 2 million pieces daily. During the peak holiday season, volumes can double, with facilities working around the clock to keep up with the surge of mail.

How Mail Gets Processed at Sorting Facilities

When a batch of mail arrives at a sorting facility, it is unloaded onto conveyor belts that carry it through the plant. The first step is singulation—separating the mail pieces so each can be scanned and sorted. Here are some of the high-tech machines that handle this process:

  • Automated Facer Canceller Systems (AFCS): These machines handle letter mail, positioning and postmarking up to 36,000 envelopes per hour. The AFCS orients mail so the address is right side up and facing out, then applies a cancellation mark to the stamp. Over 6,000 AFCS machines are in use across the USPS network.

  • Automated Package Processing System (APPS): This system is designed to sort packages, bundles, bags, and trays. It singulates and scans up to 9,500 parcels per hour, then sorts them into one of over 200 output bins. The APPS uses cameras and barcode readers to process packages of all shapes and sizes.

  • Robotic Containerization System (RCS): Some facilities are using robotic arms to automate parcel singulation. The RCS picks up packages from a hopper and places them on a conveyor belt, positioning barcodes face up for scanning. This system allows for continuous sorting and reduces the need for manual handling.

After singulation, mail pieces enter Multiline Optical Character Readers that scan the address information. The machines read the address and spray a fluorescent barcode on the mail piece, which is used to route it through the rest of the sorting process.

The barcoded mail then enters sorting machines that separate mail by ZIP code. These massive machines have hundreds of bins, each corresponding to a ZIP code or range of ZIP codes. Diverter gates and hydraulic arms called shoes sweep mail pieces into the appropriate bin as they travel along the machine at high speed.

Some facilities have more advanced sorting machines that arrange mail in delivery point sequence—the exact order in which the mail carrier delivers to addresses along their route. This final sorting step eliminates the need for carriers to manually case mail in the delivery unit.

Here is a simplified diagram showing the flow of a package through a typical sorting facility:

graph LR
A[Unload] --> B[Singulate] 
B --> C[Scan]
C --> D[Sort]
D --> E[Dispatch]

Tracking Updates from Sorting Facilities

When you check your USPS tracking, you may see statuses like "Arrived at USPS Facility" and "Departed USPS Facility." These scans indicate that your mail piece was processed at a sorting facility. The "arrived" scan occurs after the mail is unloaded and the "departed" scan happens when the mail has finished processing and is dispatched from the facility.

A "departed" scan is generally a positive sign, as it means your mail has been sorted correctly and is on the way to the next stop in the delivery chain. The next scan may show the package arriving at your local post office or out for delivery.

However, sometimes a package may seem stuck at a facility, with no new scans after departure. This does not necessarily mean the package is lost. Here are a few reasons why your tracking information may not update, along with average delay times according to USPS:

  • Miss-Sorts (1-2 days): If a sorting machine diverts your package into the wrong bin, it must be re-handled and manually sorted. Miss-sorts are rare, but can cause short delays.
  • No Space on Transport (1-2 days): Each sorting facility has cutoff times for mail to make it on the next available truck or plane. If your package misses the cutoff, it will wait until the next scheduled dispatch, usually within 24 hours.
  • Incorrect Address (2-3 days): If the machine cannot read the address or the address is deemed undeliverable, the package is shunted off for manual processing. A USPS worker must then attempt to decipher the address or return the package to sender.
  • Weather Delays (1-5 days): Inclement weather that grounds flights or closes highways can impact the departure schedule from sorting facilities. Your package will be held until transportation is available.

What To Do If Your Package Is Stuck

If your package has not moved from a sorting facility after 5 business days, the Postal Service considers it delayed. At that point, it‘s a good idea to take action:

  1. Contact USPS Customer Service at 1-800-275-8777 or through the email form at USPS.com. Have your tracking number ready.
  2. Submit a Missing Mail search request at MissingMail.USPS.com. The Postal Service will attempt to find your package.
  3. If the item has significant value, you can open a claim for loss or damage. You may be eligible for a refund or compensation.
  4. For critical deliveries, consider upgrading to Priority Mail Express, which offers a money-back guarantee if the package is not delivered by the promised time.

In most cases, your package is not actually lost, just moving slowly through the system. The Postal Service has a very high success rate, with an average of just 3 mail pieces lost per 100,000. Sorting facilities may seem like a black box, but they are a critical part of the infrastructure that keeps the mail moving.

Optimizing Packages for Faster Sortation

As a retailer or shipper, there are steps you can take to help your packages sail through sorting facilities with minimal delays:

  • Use Standard Box Sizes: Odd-shaped packages cannot be sorted by machine and must be handled manually. Using USPS-provided Flat Rate and Regional Rate packaging ensures parcels are automation-compatible.
  • Print Crisp, Clear Labels: Smudged, blurry, or handwritten labels slow down sorting because they are harder for scanners to read. Invest in a thermal printer for professional labels with scannable barcodes.
  • Include a Return Address: A return address tells USPS where to send the package if it cannot be delivered as addressed. Without it, your package may languish in a sorting facility awaiting disposition.
  • Avoid Overstuffing: Bulging or burst packages have to be re-packaged before they can be sorted. Use appropriately-sized boxes and proper cushioning to protect the contents.

By following these best practices, your packages will spend less time in sorting facilities and arrive at their destination sooner. That means happier customers and fewer inquiries for your customer service team to deal with.

The Economic Impact of Sorting Facilities

In addition to keeping the mail moving, USPS sorting facilities also provide an economic boost to the communities they serve. According to a 2019 study by the Institute for Policy Studies, the Postal Service directly employs over 500,000 workers, making it one of the largest employers in the country.

Each sorting facility creates an average of 400 jobs, from entry-level mail handlers to advanced equipment technicians. These are stable, career-track jobs with good benefits, helping to strengthen local economies.

The Postal Service also contracts with many local businesses, such as trucking companies, to support sorting operations. This generates additional jobs and economic activity in the community.

Sorting facilities are especially important in rural areas, where USPS is often the only affordable shipping option for small businesses and consumers. Without these facilities, rural customers would have to travel farther to access postal services.

Comparison to Private Carriers

USPS is not the only game in town when it comes to sorting and delivering packages. Private carriers like FedEx and UPS operate their own networks of sorting hubs. However, there are some key differences:

  • Volume: USPS handles more volume than FedEx and UPS combined, delivering 143 billion mail pieces in 2020 compared to 15 billion for the private carriers. This massive volume requires a larger and more complex sorting network.
  • Types of Mail: While FedEx and UPS focus on parcels, USPS handles everything from postcards to pallets. This diversity of mail types requires specialized sorting equipment and processes.
  • Delivery Area: As a government service, USPS is obligated to deliver to every address in the U.S., including remote areas that are expensive to serve. Private carriers can be more selective about where they deliver, allowing for a streamlined sorting network.
  • Labor Model: The majority of USPS employees are unionized and enjoy strong job protections. This can lead to higher labor costs compared to private carriers, who rely more heavily on temporary and contract workers.

Despite these differences, all the major carriers use similar technologies and processes in their sorting operations. And they often work together, with FedEx and UPS relying on USPS for last-mile delivery in many areas.

Innovations in Mail Sorting

The Postal Service is constantly innovating to make sorting operations more efficient and accurate. Here are a few examples of new technologies being deployed:

  • Advanced Facer Canceller System (AFCS-200): This next-generation cancelling machine has high-definition cameras and faster processing speeds, enabling it to handle up to 36,000 mail pieces per hour with greater precision.
  • Robotic Sorting: In addition to the Robotic Containerization System mentioned earlier, the Postal Service is testing other robotic solutions to reduce manual handling of packages. This includes autonomous guided vehicles to move mail around facilities and robotic arms to sort packages into bags and trays.
  • Predictive Maintenance: The Postal Service is using sensors and machine learning to monitor the health of sorting equipment and predict when maintenance is needed. This helps avoid unexpected downtime and keeps the mail flowing smoothly.
  • Informed Visibility: This system provides real-time tracking data on mail pieces as they move through the sorting network. This allows USPS to optimize the flow of mail and quickly identify and resolve issues.

These innovations, combined with ongoing process improvements, help the Postal Service stay competitive in a rapidly evolving market. By investing in new technologies, USPS is working to provide faster, more reliable service for customers.

Conclusion

The next time you‘re waiting on a package, remember all the high-tech processing that happens at sorting facilities to get mail where it needs to go. The U.S. Postal Service delivers more mail to more addresses than any other post in the world, all thanks to the powerhouse sorting plants that keep it all running.

A "departed facility" scan means your mail is one step closer to arriving at your doorstep. While delays can happen, the vast majority of packages move smoothly through the sorting network and arrive on time.

As e-commerce continues to grow, USPS sorting facilities will play an even greater role in keeping the economy moving. By providing affordable, reliable shipping services to businesses and consumers alike, the Postal Service is helping to connect communities and power economic growth.

So let‘s hear it for the hardworking men and women of the USPS, who keep the mail moving rain or shine. And let‘s marvel at the technological wonders that are sorting facilities, the unsung heroes of the postal world.