Eh, at least in my experience, interest in most normal mortgages ends up less than the standard deduction so it can’t be claimed. It was a change Trump made to the tax code I think. I don’t understand enough about it to know if it affects me negatively or not. I know it’s better for me to claim the standard deduction instead of itemizing my deductions. This means I can’t claim interest paid (which is bad), but the standard deduction is higher than it was before, so I think I’m still claiming more money as untaxable (which is good, I think?).

Maybe someone with more knowledge than me can chip in.

I don’t thing it’s location specific. It’s more like a pie chart where it’s grouping the similar land typess together and then arbitrarily placing them on the US map.