At today’s rates, monthly payments on a $500,000 home would stand at roughly $3,265 after putting 20% down. That’s $1,165 more than two years ago, when mortgage rates were barely above 3%.

No one set out to make the 30-year mortgage the standard. It is “a bit of a historical accident,” said Andra Ghent, an economist at the University of Utah who has studied the U.S. mortgage market.