I see that the rising rates is part of the cause. Why were rates so low? My mortgage is financed at 2.25%, but it seems obvious that the Federal Discount Rate r

I see that the rising rates is part of the cause. Why were rates so low? My mortgage is financed at 2.25%, but it seems obvious that the Federal Discount Rate rate would rise over the 30 years of the mortgage. Why do 30 year mortgage rates follow the Fed rate so closely in the first place?