Highways in Peru
The primary highways of Peru are assigned using a numeric designation and sometimes a name. Spur and loop routes are designated with the parent highway's number and a letter (excluding N or more than one occurrence of S). Longitudinal highways (travelling north to south) are designated with odd numbers. They are numbered from smallest to largest from the west to the east. Transverse highways (travelling east to west) are designated with even numbers. They are numbered from smallest to largest from the north to the south.