Morgans wrote:


State plane?

UTM?

There are other coordinate systems than lat/long. A state plane picks
an arbitrary place in the state and measures in feet (or meters) from
that North and East. Similarly, Universal Transverse Mercator chops up
the earth into 3 degree zones and then makes meters north and east from
a reference point in that zone.

It's a bit more involved than that, but it's good enough for the precision
of what unassisted GPS is going to give you.