USPS SERVICE STANDARDS, JULY 1 2026 - parsed by Hamdi Saidani, deliverytimecalculator.com
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SOURCE
  USPS 3D Base Service Standard Directory, effective July 1 2026
  (3D_Base_Service_Standard_Directory_07012026.csv)
  Download page:       https://postalpro.usps.com/service-standards/3d-base
  Column definitions:  USPS "SSMP Service Standards File Layout" (PDF)
                       https://postalpro.usps.com/mnt/glusterfs/2025-10/SSMP%20Service%20Standards%20File%20Layout.pdf
  NOT included yet: the Supplemental Service Standard Directory (5-digit origin exceptions, one
  file per class at https://postalpro.usps.com/Suppl_SSD_FCM, /Suppl_SSD_PRI, /Suppl_SSD_GAL ...).
  The base file is therefore the best case. A version with the supplemental applied is coming.

FILES
  1. usps-service-standards-3digit-pairs-2026-07-01.zip   (CSV inside, 849,106 rows, 914 origins)
     One row per origin 3-digit ZIP prefix x destination 3-digit ZIP prefix.
     origin_zip3, origin_state, dest_zip3, dest_state,
     lower48_pair                  Y when both ends are in the 48 contiguous states or DC
     first_class_mail_days       = FCM  First-Class Mail letters and flats, single piece
     priority_mail_days          = PRI  Priority Mail
     ground_advantage_light_days = GAL  USPS Ground Advantage up to 15.999 oz
     ground_advantage_heavy_days = GAH  USPS Ground Advantage 16 oz and over
     package_services_days       = PKG  Package Services (Media Mail, Library Mail, Bound Printed Matter)
     marketing_mail_days         = MKT  USPS Marketing Mail
     periodicals_days            = PER  Periodicals
     presort_first_class_days    = PFC  Presort First-Class Mail
     Empty cell = USPS publishes no standard for that pair and class.

  2. usps-service-standards-state-to-state-2026-07-01.csv
     Lower-48 pairs only, grouped by origin state x destination state: number of 3-digit pairs,
     then average / min / max days for FCM, PRI, GAL, GAH, PKG.

  3. usps-service-standards-by-origin-state-2026-07-01.csv
     Each origin state to every lower-48 3-digit area: average / min / max days per class, and the
     share of routes that are 5-day (First-Class), 2-day (First-Class), 2-day (Priority),
     5-day (Ground Advantage light).

  4. usps-service-standards-by-dest-state-2026-07-01.csv
     Same idea, by destination state.

CAVEATS
  - Averages count every 3-digit pair once. They are NOT weighted by mail volume or population.
  - These are the published standards (the promise), not measured performance.
  - AK, HI, PR, VI, GU, AS, MP and military prefixes are in file 1 with lower48_pair = N and are
    excluded from the summaries.
  - State per 3-digit prefix follows the USPS prefix ranges; all 932 prefixes in the file are mapped.

LOWER-48 SHARE OF ROUTES BY STANDARD (from file 1, 814,506 pairs)
  First-Class Mail:   2-day 4.2%   3-day 24.3%   4-day 39.4%   5-day 32.1%
  Priority Mail:      2-day 18.0%  3-day 82.0%   (no 1-day route)
  Ground Advantage:   2-day 9.7%   3-day 33.8%   4-day 38.4%   5-day 18.0%   (light and heavy are identical in the lower 48)
  Package Services:   4-day 9.7%   5-day 33.8%   6-day 38.4%   7-day 18.0%