39 USC § 3631 - Applicability; definitions and updates

---
identifier: "/us/usc/t39/s3631"
source: "usc"
legal_status: "official_legal_evidence"
title: "39 USC § 3631 - Applicability; definitions and updates"
title_number: 39
title_name: "POSTAL SERVICE"
section_number: "3631"
section_name: "Applicability; definitions and updates"
chapter_number: 36
chapter_name: "POSTAL RATES, CLASSES, AND SERVICES"
subchapter_number: "II"
subchapter_name: "PROVISIONS RELATING TO COMPETITIVE PRODUCTS"
part_number: "IV"
part_name: "MAIL MATTER"
positive_law: true
currency: "119-84"
last_updated: "2026-03-26"
format_version: "1.1.0"
generator: "[email protected]"
source_credit: "(Added Pub. L. 109–435, title II, § 202, Dec. 20, 2006, 120 Stat. 3205.)"
---


# § 3631. Applicability; definitions and updates

**(a)** **Applicability.—** This subchapter shall apply with respect to—

subject to subsection (d) and any changes the Postal Regulatory Commission may make under section 3642.

**(1)** priority mail;

**(2)** expedited mail;

**(3)** bulk parcel post;

**(4)** bulk international mail; and

**(5)** mailgrams;

**(b)** **Definition.—** For purposes of this subchapter, the term “costs attributable”, as used with respect to a product, means the direct and indirect postal costs attributable to such product through reliably identified causal relationships.

**(c)** **Rule of Construction.—** Mail matter referred to in subsection (a) shall, for purposes of this subchapter, be considered to have the meaning given to such mail matter under the mail classification schedule.

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**Source Credit**: (Added Pub. L. 109–435, title II, § 202, Dec. 20, 2006, 120 Stat. 3205.)