SOUTH PORTLAND – There’s nothing extraordinary about a certain four-bedroom, one-bath house on Cole Street except for this: The house sold last year for $195,000, twice the price it fetched 10 years ago.

Half a mile away, a three-bedroom bungalow that overlooks the Fore River tripled in value from 1985, selling last year for $229,900.

In another part of the city, a house that sold for $51,000 in 1986 brought a whopping $259,000 last year, a fivefold increase.

The place where residential property values shot upward the fastest over the past two decades was not San Francisco, New York or Boston. It was right here in Greater Portland, by at least one measure.

Between 1983 and 2002, the median price for existing single-family homes in Cumberland County rose from $38,600 to $178,670, according to Economy.com Inc., a financial research company in West Chester, Pa.

That amounts to an 8.4 percent yearly increase from 1983-2002 – nearly four times the 2.2 percent annual rise nationwide. It’s also ahead of other rapid-rising markets like Boston (8.2 percent); San Francisco (7.6 percent); San Diego (7.1 percent); Providence, R.I. (6.8 percent); and New York (6.8 percent).

People who have bought or sold houses in Cumberland County can attest to the swift appreciation of recent years. But the numbers over the past two decades seem to elicit a common response: “Wow.”

“While I’m not shocked, I’m surprised,” said Steve Hammond, a real estate agent and consultant who has been involved in the Portland-area real estate market for more than 25 years. “I just never considered putting our inflation rate in the same ranks as Boston or California.”

Valarie Lamont, director of the Institute for Real Estate Research and Education at the University of Southern Maine, questioned the numbers – she thinks the 1983 median price was probably higher than $38,600. Still, she says, “That doesn’t mean we haven’t had high appreciation.”

The prices are continuing to go up this year.

For the second quarter of the year, the median home price in Portland was $197,500, up 11.5 percent from a year earlier, the National Association of Realtors reported this month. As recently as 1999, Portland home prices were below the U.S. median; they are now 17 percent above the national median.

The rising prices are due in part to supply and demand. The population in Cumberland County increased 9.2 percent in the 1990s, much faster than the state as a whole, which grew 3.8 percent, according to the U.S. Census.

Low mortgage rates have also fed into demand that has driven up prices. Low rates allow people to have lower monthly payments for higher-priced homes and provide encouragement to first-time home buyers.

Despite it all, Maine still seems like a bargain to out-of-state buyers who have been snapping up seasonal homes in southern Maine, said Bill Zafirson, Maine sales manager for Banknorth Mortgage Group.

“People look to Maine and look at the real estate as a bargain compared to other places in the country,” he said.

The Portland-area market rose fast in the mid-1980s, then declined and stagnated in the early ’90s before coming back to life six or seven years ago. Many people who bought homes at the peak in the late ’80s sold at a loss in the years to come.

But for those who bought in the early ’80s or the early to mid-’90s, the rewards can be handsome if they’ve sold their properties the past couple of years. For some, the appreciation means moving up to bigger homes, or retiring with larger nest eggs.

The high prices, however, have made it harder for first-time homeowners to get into the market. Dave Flaherty, owner of Flahetry Realty in Brunswick, bemoans the fast rise in home prices.

“We want slow moderate growth,” Flaherty said.

Celia Chen, a senior economist with Economy.com, said Portland is among the markets that are considered “highly overpriced.” Others include San Francisco and San Jose, Calif., Boston, and the suburbs around New York City.

Given that, Portland could be susceptible to a real estate correction where prices drop, if not dramatically at least somewhat.

Which means home owners shouldn’t get too used to the home prices going up fast forever. Walt Maloney of the National Association of Realtors said the normal growth rate for real estate should be 1 or 2 percentage points above the consumer price index.