The interest rate on a 20 year fixed mortgage can sometimes be lower than the interest rates on a 30 year fixed mortgage.
Although you'll usually pay a much higher monthly payment on the 20 year fixed mortgage vs the 30 year fixed mortgage but you'll have the mortgage paid off 10 years sooner and save quite a bit of money in interest over the life of the mortgage.
Rates for a 20 year fixed mortgage are between 3.875% and 3.905% which is cheaper than the rates on a 30 year mortgage.
I started out buying my home using a 30 year mortgage but 8 years in I refinanced the 30 year mortgage to a 20 year mortgage which lowered my interest rate although I have a higher monthly payment.
I refinanced because I got a better job and could afford the extra monthly payments which will pay off the home sooner than waiting 30 years which is a pretty long time.