The number of loans guaranteed by the Department of Veterans Affairs reached a record high in 2013, perhaps marking the peak of an upward trajectory that began after the housing market collapse.

The department guaranteed nearly 630,000 mortgage loans in fiscal year 2013, setting a new high just as the program enters its 70th year, said Mike Frueh, the director of the V.A.’s Loan Guaranty Program. The average loan was about $225,000, an amount that reflects the program’s value to “working-class America,” he said.

Calling the program’s growth “pretty incredible,” Chris Birk, the executive editor at Veterans United Home Loans, an online broker of V.A. loans, estimated that total loan volume has risen 372 percent since fiscal 2007.

One reason is historically low interest rates, which have driven a tremendous increase in loans for the purpose of refinancing. About half of last year’s V.A. loans were “refis.” That business dropped off toward the end of last year as interest rates rose.