Cascadian Highway System

(Higher quality map at the bottom of bulletin)
In the Dominion of Cascadia, there are 4 main highways, and 10 interstates. 

The four main highways are called the Cross-Cascadian Highways, or CCH. 
The individual highways are called CCH-N(orth), CCH-C(entral), CCH-S(outh), and CCH-W(est).
These highways connect the nation from Juneau to Las Vegas, and Masset to Salt Lake City, and Eugene to San Diego. 
CCH-N spans from Victoria City to Juneau, CCH-C spans from New Portland to Victoria City, CCH-S spans from New Portland to Las Vegas, and CCH-W spans from Eugene to San Diego. 
On the map they are a lighter yellow than the interstates
On the map and along the highway they are marked by these:

The 10 interstates are referred to as just interstates, or sometimes as the 4 marks, to distinguish them from the CCHs'.
The interstates are named by the first two letters of their beginning and ending cities*, the westernmost of the connecting cities is always the beginning city, and the easternmost is the ending.
For example, the RE-LV interstate starts in Reno, Sierra, and ends in Las Vegas, Sierra. BE-RE starts in Bend, Oregon, and ends in Reno, Sierra. This is also why they are sometimes called the 4 marks.
Above on the map they are a more defined and darker yellow from the CCHs'.
On the map and along the interstates they are marked by these: 

 

*Only applies if the city only has one name, if the city has two words in it's name (Ex: Las Vegas, Seattle-Tacoma) or if the city name is a compound word (Ex: Portland), then the first letter of both words will be used (Ex: Portland is PL, Las Vegas is LV, and Seattle-Tacoma is ST)