According to Freddie Mac, the average rate for a 30-year loan now stands at 4.1 percent. That is the lowest level since June 2013.
The average rate for a 15-year fixed loan is 3.23 percent.
The government's stimulus program has helped keep borrowing costs down.
The federal reserve has been purchasing treasury bonds and mortgaged-backed securities for years, providing a steady market for mortgages.
But the fed has cut back on its purchases, and plans to end the buying program entirely in October, reducing demand for mortgage bonds.
That should eventually cause rates to climb.