[RadioAstronomer]

I've driven clear across the U.S. before without ever considering the curvature of the earth. I don't even have a road map that shows it.

Except the map makers took the curvature into consideration or the miles would not be accurate.

[templar]

Except the map makers took the curvature into consideration or the miles would not be accurate.

You've never worked on a survey crew. The map makers probably used the direct distance measuremnts done by the surveyors, actual measurement of distance from place to place, something that has been doen since long before the spherical concept of the earth was developed (Roman maps and roads from 2000+ years ago are quite good). Basically, you just set yourself on a heading and go in a straight line in that direction and you arrive at your destination (grravity compensates for the earth's curvature so that you don't end up out in the vacuum somewhere on a long journey. You don't even have to think about it, it's all automatic. Same way you don't have to remember to breathe, it just happens).

[El Gato]

And of course one doesn't navigate directly from say Miami to Seattle with no intermediate stops or way points. Road maps don't really show geometric relationships except in a "connectedness" sense and a general direction. If you took the map of the US in your road atlas and measured the apparent direction from Miami to Seattle and headed off that direction, and had a "perfect" compass to keep you heading that direction, you'd miss Seattle by quite a bit. You wouldn't even actually go in a straight line, or great circle, path.