In cartography, the concept of True North may be slightly different in different parts of the county, the state, or the country. When cartographers got together many years ago to hash out some of their different practices, they decided to essentially invent a system that would describe the earth's surface as an approximation of a spheroid.
They came up with the geoid. You are actually pretty familiar with one of the more recent geoids, because its ubiquity is now such that it is a part of your life.
That's because the US Navy, years ago, thought that their current navigation systems were a hodgepodge of ancient relics and technology that was ridiculous. And inaccurate. Even their early version of satellite navigation was pathetic. So they put a few satellites in the air and called the system NAVSTAR. You might know it as the Global Positioning System, GPS.
And so while naval vessels certainly have gyrocompasses galore, and they can break out the old celestial navigation instruments and books, the go-to way of determining position and compass heading is with very fast and very accurate position fixes from GPS.
But going back to the geoid, which is going to be "WGS 84" (1984) for most GPS fixes, the cartographers were able to successfully correlate a local position with a global position. So if "north" in Fairfax county is a few minutes off of true north, or if the "latitude" of positions in Arlington County tends to be 24.3 m south of the global geoid, then a cartographer can account for this.
So if a position needs to be offset in one region, and stretched in another region, the reference geoid is used for the "conversion" as bearing lines pass from one place to another. You will discover that most insular areas of a country have historical boundaries and waterways which are peculiar to that country. So in the US, there is a place allegedly called "Four Corners," which separates for states. It was pinpointed about "1807 feet east of where it should have been placed in 1875."
So to get back to your question, you may be surprised to learn that some old surveyors used literal links and chains, and that sometimes their compass was no more than the apparent line of sight from a "known" position to an unknown position that was halfway to another "known" position.
And due to historical errors, the "north-south" property line or the east-west state line near you could be a jagged, seemingly arbitrary, non-true anything.
One of the old types of satellite navigation which I failed to mention earlier utilized satellites in polar orbit. This type of orbit is quite a useful one, especially for cartography and communication. You can use this type of satellite on a clear night to find a north-south line. So while you may know how to do celestial navigation, or be able to follow a pole star, a satellite in low polar orbit will be visible, rapidly transiting the sky from north to south. This works in both hemispheres, too, in case you find yourself way down under.
So that gives you three more virtual compasses: 1. the cartographer's and surveyor's grid coordinate systems that trickle down to us as fence lines and
national borders. 2. the geoid-inspired compass that's on your cell phone. And 3. the north-south path of polar orbiting satellites. #1 and #3 can be used without carrying anything with you.