USPS RTO Lookup by ZIP Code
Is your post office on USPS's Regional Transportation Optimization (RTO) list?
Type a ZIP code to see its post office, whether the RTO truck change has started there, and the last day to mail.
The data is USPS's own, from its filings at the Postal Regulatory Commission: 28,540 ZIP codes, updated with the report of August 3, 2026.
Is Your Post Office on the RTO List?
Type the ZIP code the mail is sent from.
You get its post office and plant, whether the RTO truck change has started there, and what it means for your mail.
USPS data: RTO list of January 16, 2026, monthly report of August 3, 2026.
Last Day to Mail
- Being on the list does not set the days by itself: USPS says both ZIP codes count.
- Add where the mail is going and the day it must arrive.
- The dates use USPS's July 2026 standards, with the extra day for ZIP codes far from their plant included.
The day it must be delivered.
What Is USPS RTO?
RTO (Regional Transportation Optimization) is a USPS change for post offices more than 50 miles from their regional processing plant.
Before: two trucks a day. One in the morning with mail to deliver, one later to take the day's outgoing mail to the plant.
Now: typically one trip a day. Outgoing mail leaves the next morning instead of the same evening.
The extra day
- Since April 1, 2025, USPS adds one day for First-Class Mail and Ground Advantage sent from offices more than 50 miles from their plant.
- Presorted First-Class Mail is not changed.
What does not change
- Post office hours.
- Carrier delivery and pickups, and collection from blue boxes.
- Only the time the mail leaves for the plant changes (USPS).
Not every route slows down
- USPS says the days still depend on both ZIP codes.
- Many routes from RTO offices kept their old standard, because USPS also widened how far mail can travel in 2, 3 or 4 days.
- That is why the calculator above uses your exact route.
The review
- The Postal Regulatory Commission reviewed the plan in docket N2024-1 and gave its advisory opinion on January 31, 2025.
Sources: USPS, Changes in Service Standards: FAQs (updated February 9, 2026); Postal Regulatory Commission, Nationwide Changes to Mail Service.
Our Finding: USPS's Slower ZIP Codes Are RTO ZIP Codes
13,286 of the 13,333 ZIP codes on USPS's slower list for First-Class Mail (99.6%) are on the RTO list.
The slower list is in USPS's Supplemental Service Standard Directory (July 2026). It names the ZIP codes whose mail takes longer than the rest of their 3-digit area.
We compared it with USPS's RTO list, ZIP code by ZIP code.
| Mail class | ZIP codes on the slower list | On the RTO list | Share |
|---|---|---|---|
| First-Class Mail | 13,333 | 13,286 | 99.6% |
| Ground Advantage | 10,562 | 10,515 | 99.6% |
| Priority Mail | 22,541 | 10,693 | 47.4% |
What it means
- For First-Class Mail and Ground Advantage, the two lists are almost the same. This is the extra day USPS added in 2025 for mail sent from offices more than 50 miles from their plant.
- How many routes get it varies a lot. Some ZIP codes get it to almost every area, others only for mail to nearby areas. The lookup shows the count for each ZIP code.
- The day was added whether or not the truck change had started. By the report of August 3, 2026, RTO had started in 6,786 of the 13,333 slower First-Class Mail ZIP codes.
- Priority Mail's slower list is different: fewer than half of its ZIP codes are RTO ZIP codes.
How we checked
- 5-digit ZIP codes, exactly as USPS lists them in both files.
- The RTO list here is the 28,540 ZIP codes of January 16, 2026, plus 4 more that appear only in the report of August 3, 2026.
- You can check it yourself with the free download below.
RTO by State
- USPS's list has post offices in all 48 states of the lower 48.
- Alaska, Hawaii, the District of Columbia and Puerto Rico have none.
- Most RTO ZIP codes: Texas (1,697), then New York (1,497) and Pennsylvania (1,362).
- "RTO started" counts the ZIP codes with a start date in the report of August 3, 2026.
| State | Post offices | ZIP codes | RTO started |
|---|---|---|---|
| Alabama | 456 | 631 | 0 |
| Arizona | 226 | 319 | 55 |
| Arkansas | 565 | 685 | 492 |
| California | 888 | 1,251 | 669 |
| Colorado | 321 | 441 | 182 |
| Connecticut | 172 | 286 | 0 |
| Delaware | 46 | 75 | 0 |
| Florida | 425 | 725 | 203 |
| Georgia | 542 | 710 | 37 |
| Idaho | 206 | 250 | 73 |
| Illinois | 903 | 1,130 | 688 |
| Indiana | 504 | 722 | 322 |
| Iowa | 668 | 865 | 297 |
| Kansas | 478 | 664 | 544 |
| Kentucky | 521 | 798 | 199 |
| Louisiana | 494 | 710 | 331 |
| Maine | 314 | 359 | 324 |
| Maryland | 239 | 315 | 264 |
| Massachusetts | 185 | 225 | 87 |
| Michigan | 630 | 779 | 257 |
| Minnesota | 585 | 720 | 535 |
| Mississippi | 409 | 496 | 0 |
| Missouri | 620 | 880 | 539 |
| Montana | 299 | 369 | 156 |
| Nebraska | 394 | 517 | 420 |
| Nevada | 96 | 140 | 61 |
| New Hampshire | 207 | 260 | 216 |
| New Jersey | 180 | 218 | 178 |
| New Mexico | 278 | 354 | 35 |
| New York | 1,195 | 1,497 | 696 |
| North Carolina | 595 | 774 | 228 |
| North Dakota | 248 | 372 | 79 |
| Ohio | 707 | 946 | 54 |
| Oklahoma | 483 | 618 | 0 |
| Oregon | 296 | 351 | 286 |
| Pennsylvania | 1,055 | 1,362 | 1,108 |
| Rhode Island | 54 | 79 | 62 |
| South Carolina | 303 | 415 | 112 |
| South Dakota | 294 | 382 | 184 |
| Tennessee | 437 | 563 | 83 |
| Texas | 1,255 | 1,697 | 815 |
| Utah | 158 | 208 | 51 |
| Vermont | 262 | 309 | 257 |
| Virginia | 651 | 927 | 561 |
| Washington | 330 | 393 | 334 |
| West Virginia | 595 | 847 | 637 |
| Wisconsin | 598 | 715 | 226 |
| Wyoming | 139 | 191 | 58 |
| Total | 21,506 | 28,540 | 12,995 |
When RTO Started: ZIP Codes by Month
- USPS started the truck change in February 2025.
- By the report of August 3, 2026, it had started in 12,999 ZIP codes, most recently in July 2026.
- USPS's report notes there were no starts in April 2025 or December 2025.
- Each ZIP code is counted in the month of its first start date. 200 ZIP codes have two dates in the report; the lookup shows both.
| Month | ZIP codes |
|---|---|
| February 2025 | 104 |
| March 2025 | 1,401 |
| May 2025 | 2,904 |
| June 2025 | 67 |
| July 2025 | 815 |
| August 2025 | 873 |
| September 2025 | 1,040 |
| October 2025 | 971 |
| November 2025 | 382 |
| January 2026 | 1,687 |
| February 2026 | 147 |
| March 2026 | 489 |
| April 2026 | 1,472 |
| May 2026 | 426 |
| June 2026 | 119 |
| July 2026 | 102 |
Mailing a Ballot From an RTO ZIP Code
The general election is on Tuesday, November 3, 2026.
USPS's advice for every voter
- Mail the completed ballot before Election Day.
- Mail it at least one week before your election office must receive it.
- Some states ask for more time.
From an RTO post office
- Outgoing mail leaves for the plant a day later.
- USPS says a ballot envelope may not get its postmark on the day it is collected.
- To be sure of that day's postmark: hand the envelope in at the post office counter and ask for a manual (hand) postmark. It is free.
Your state's rules
- This page gives mail timing only.
- For your deadline and the rules, check your state's election office at usa.gov/election-office.
Source: USPS Election Mail and the USPS FAQ above.
Download the RTO ZIP Code List
One row per ZIP code (28,544 rows), with:
- the ZIP code, its post office and address, and the state
- its regional processing plant
- whether it is on the list of January 16, 2026
- its RTO start date or dates, from the report of August 3, 2026
- Free to use. Please credit "deliverytimecalculator.com, from USPS filings at the Postal Regulatory Commission".
- To link to one ZIP code's answer, add ?zip= and the ZIP code: /usps-rto-lookup?zip=12574
Sources
- The RTO list: USPS response to ACR2025 Chairman's Information Request No. 1, question 28 (Postal Regulatory Commission filing 139072, January 16, 2026). USPS does not publish this list on usps.com.
- Where RTO has started: USPS Sixteenth Report, docket RM2024-9 (filing 140575, August 3, 2026). USPS files a new report every month; we update this page when it does.
- The rules: USPS, Changes in Service Standards: FAQs (updated February 9, 2026).
- The slower ZIP codes: USPS Supplemental Service Standard Directory, July 2026 (postalpro.usps.com), the same data our calculators use.
- Thanks to Save the Post Office, which pointed us to these filings and has followed RTO since the start, with its own RTO map.
Frequently Asked Questions
What is USPS RTO?
RTO (Regional Transportation Optimization) is a USPS change for post offices more than 50 miles from their regional processing plant.
USPS used to send two trucks a day to each of these post offices; under RTO there is typically one, so outgoing mail collected during the day goes to the plant the next morning instead of the same evening.
How do I know if my post office is on the RTO list?
Type your ZIP code in the lookup on this page.
USPS does not publish the list on usps.com; it gave it to the Postal Regulatory Commission on January 16, 2026 (21,506 post offices serving 28,540 ZIP codes) and reports every month where RTO has started.
Does RTO slow down my mail?
It can slow down mail you send from an RTO post office.
Since April 1, 2025, USPS adds one day to its delivery standard for First-Class Mail and Ground Advantage sent from offices more than 50 miles from their plant; presorted business mail is not changed.
USPS also says many routes keep the same standard as before, because it widened how far mail can travel in 2, 3 or 4 days. The calculator on this page gives the dates for your exact route.
Does RTO slow down mail I receive?
Not because of your own post office. RTO adds its day where mail is sent from. Mail sent to you from another RTO post office can take a day longer; mail sent from a city near a plant is not slowed by RTO.
Does RTO change post office hours or blue box pickups?
No. USPS says RTO does not change post office hours, carrier delivery or pickups, or collection from blue boxes. What changes is when the collected mail leaves for the processing plant.
How should I mail a ballot from an RTO post office?
USPS's advice for all voters: mail your completed ballot before Election Day and at least one week before your election office must receive it.
To be sure of that day's postmark, hand it in at the post office counter and ask for a manual postmark, which is free. Always check your state's rules.