It was pointed out that different locations have more or less strong dependence on the difference between true and magnetic north. And it depends strongly on East-West location. For example, in Minnesota, it's only a degree or so difference, but in PA it can be 10-15 deg.
It was pointed out that different locations have more or less strong dependence on the difference between true and magnetic north. And it depends strongly on East-West location. For example, in Minnesota, it's only a degree or so difference, but in PA it can be 10-15 deg.