- Title 1 General Provisions
- Title 2 The Congress
- Title 3 The President
- Title 4 Flag and Seal, Seat Of Government,and the States
- Title 5 Government Organization and Employees
- Appendix to Title 5
- Title 6 Domestic Security
- Title 7 Agriculture
- Title 8 Aliens and Nationality
- Title 9 Arbitration
- Title 10 Armed Forces
- Appendix to Title 10 (Rules of Court of Appeals for the Armed Forces)
- Title 11 Bankruptcy
- Appendix to Title 11
- Title 12 Banks and Banking
- Title 13 Census
- Title 14 Coast Guard
- Title 15 Commerce and Trade
- Title 16 Conservation
- Title 17 Copyrights
- Title 18 Crimes and Criminal Procedure
- Appendix to Title 18
- Title 19 Customs Duties
- Title 20 Education
- Title 21 Food and Drugs
- Title 22 Foreign Relations and Intercourse
- Title 23 Highways
- Title 24 Hospitals and Asylums
- Title 25 Indians
- Title 26 Internal Revenue Code
- Appendix to Title 26
- Title 27 Intoxicating Liquors
- Title 28 Judiciary and Judicial Procedure
- Appendix to Title 28
- Title 29 Labor
- Title 30 Mineral Lands and Mining
- Title 31 Money and Finance
- Title 32 National Guard
- Title 33 Navigation and Navigable Waters
- Title 34 Navy (repealed)
- Title 35 Patents
- Title 36 Patriotic Societies and Observances
- Title 37 Pay and Allowances Of the Uniformed Services
- Title 38 Veterans' Benefits
- Appendix to Title 38 (Rules of Court of Appeals for Veterans Claims()
- Title 39 Postal Service
- Title 40 Public Buildings, Property, and Works
- Title 41 Public Contracts
- Title 42 The Public Health and Welfare
- Title 43 Public Lands
- Title 44 Public Printing and Documents
- Title 45 Railroads
- Title 46 Shipping
- Appendix to Title 46
- Title 47 Telegraphs, Telephones, and Radiotelegraphs
- Title 48 Territories and Insular Possessions
- Title 49 Transportation
- Title 50 War and National Defense
- Appendix to Title 50
U.S. Code > Title 39 Postal Service > PART IV—MAIL MATTER (§§ 3001—3691) > CHAPTER 36—POSTAL RATES, CLASSES, AND SERVICES (§§ 3621—3691) > SUBCHAPTER VII—MODERN SERVICE STANDARDS (§ 3691)