The 30-year, fixed-rate mortgage averaged 4.78 percent with an average 0.7 points in the week, Freddie Mac said.
A week ago, 30-year, fixed-rate mortgages averaged 4.85 percent. A year ago the average rate was 5.88 percent. The long-term rate is lower than it has been since Freddie Mac began the weekly survey in 1971, the lender said in a statement.
At 4.52 percent with an average 0.7 points, the 15-year, fixed-rate average is at its lowest point since 1991, Freddie Mac said.
Last week, 15-year, fixed-rate mortgages averaged 4.58 percent. A year ago, they averaged 5.42 percent.
"Mortgage rates followed other interest rates lower this week amid reports of slower economic growth," said Frank Nothaft, Freddie Mac vice president and chief economist.
Nothaft noted that fixed-rate mortgages "are currently the predominant choice among homebuyers and families looking to refinance."
"On a positive note, pending existing home sales rose 2.1 percent in February, marking the second increase in three months as potential homebuyers are taking advantage of historically low mortgage rates and falling home prices," he said.