### Question
What does mainline route mean?


### Answer
**Mainline route** has the following meaning in *39 U.S.C. § 5402*:

> a city pair in which a mainline carrier is tendered nonpriority bypass mail

#### Citation:
  - *39 U.S.C. § 5402*
  - Heading: **PART V-TRANSPORTATION OF MAIL > CHAPTER 54-TRANSPORTATION OF MAIL BY AIR**

