According to data from an American real estate consultancy, just under 30 per cent of American homeowners own their home outright, free of any sort of mortgage on the property.

Zillow said Thursday 20.6 million Americans, or 29.3 per cent of all U.S. homeowners, aren't encumbered by a mortgage.

U.S. policymakers keep a keen eye on the housing market, as it was the epicentre of the financial crisis that plunged the American economy into recession in late 2007. The 30 per cent figure is roughly in line with historical averages.

"Looking at those homeowners who are free-and-clear is important," Zillow's chief economist Stan Humphries said. "Homeowners unencumbered by a mortgage may be more flexible than indebted homeowners, and therefore more apt or willing to list their homes or enter the market for a new property."

Zillow's data found wide regional variations in the ratio of paid-off homeowners. Among the 30 largest U.S. cities, the ratio was highest in Pittsburgh at 38 per cent, followed by Tampa at 33 per cent.

Conversely, Washington D.C. (15.5 per cent) Atlanta (17.7 per cent) and Las Vegas (18.3 per cent) had the three lowest ownership ratios in the country.

Not surprisingly, Zillow found that on average, areas with cheaper housing prices have generally have higher outright homeownership rates, as smaller loan amounts are easier to pay back more quickly.

Demographic factors

Zillow also found that broadly speaking, the older you are, the more likely you are to own your own home. Those between the age of 65 and 74 are most likely to be free-and-clear (at 20.5 per cent), followed by 74- to 84-year-olds at 17.9 per cent.

But there is a curious outlier to that trend: "Interestingly, when examining free-and-clear ownership rates as a percentage of homeowners in various age groups, Zillow found 34.5 per cent of 20- to 24-year-old homeowners are free of mortgages," the company said.

The 30 per cent figure across American homeowners as a whole is encouraging news for U.S. policymakers, who worry about an extended moribund housing market in many parts of the country. Almost four million homeowners went into foreclosure in 2012, official data show.

But America's 30 per cent national ratio is actually well under Canada's number. According to the Canadian Association of Accredited Mortgage Professionals, there are currently about 9.85 million homeowners in Canada, of whom about 5.85 million have mortgages.

The remaining 3.75 million Canadian homeowners are mortgage-free, which means 38 per cent of Canadian homeowners own their own homes outright.