A California-based developer has announced plans to sell the remaining undeveloped land in Marlton, a massive 2,000-acre planned community in southern Prince George's County that was left half-finished in the late 1970s.

If it is ever completed, Marlton will be the home of an estimated 20,000 people, with 6,300 houses, town houses and apartment units, plus schools, shopping centers and a 79-acre office park -- enough to rival such mini-cities as Konterra and Columbia.

"It's the first and only Residential Planned Community in the county under the first RPC law of 1948," said sales agent Larry Hogan Jr. of Marlton, which was zoned in 1968. "It is completely planned, zoned and ready for development."

Marlton, on Route 301 about 15 miles from downtown Washington, was started by a handful of farm owners who applied for the RPC zoning back in the 1960s and constructed many of the original houses. They sold the development to an Idaho-based investment firm, which sold it, in turn, to Larwin Developments Inc. of Encino, Calif., in the late 1970s, said company spokesman Barbara Richman.

"Larwin hit the big housing slump in the late 1970s, so the community was never finished," she said. "Interest rates were high and gas prices were high. The commute seemed long at that time."

Since then, Marlton has been a quiet half-completed community of single-family homes, a small shopping center and a swimming pool surrounded by heavily wooded land. More than 6,200 residents live there in homes that once sold for $24,000 but now go for $124,000 and more.

Last year, Larwin, which had shut down its East Coast projects, took another look at Marlton and decided the time was ripe to sell the remaining 1,000 acres of undeveloped, but already zoned, property, Richman said. She said few developers were interested in purchasing the whole tract, however, because "no one wanted to take such a big risk."

So the development company has split the property into 19 parcels ranging in price from $6,990 to $1.9 million and totaling $9.7 million. Each parcel already is zoned and some have preliminary subdivision plans, although the county has not granted final approval for any subdivision on the property.

For example, a 7.9-acre parcel billed as property 3 West is zoned for 32 town-house units and is selling for $112,000. Water and sewer lines and access roads are nearby, Richman said.

"Since we've split it up like this, we've had a lot of inquiries," said Richman, who would not say which developers have expressed an interest in the properties. "They see it as a nice, low-risk package."

Hogan, who is marketing the land, said developers are more interested in the parcels zoned for single-family homes and town houses and said developers have shown little interest in the industrial park and commercially zoned parcels.

"There is a change in attitude about this area of the county," he said. "Now the time is ripe to develop residentially. But the trend is to low density. There are quite a lot of office parks in the Washington area and competition is high."

Hogan said he believes it will take 15 years before the high-rise apartment buildings and acres of commercial and industrial buildings are constructed in Marlton, even though the zoning for them was approved years ago. Real estate agents in the Marlton area said home sales in the community are brisk compared with sales in other parts of Prince George's County, and they say there will be a demand for new residential units in the town.

"Marlton is considered desirable because it has covenants that are strictly enforced," said agent Hildy Cardaci of the Mt. Vernon Real Estate Agency in Marlton Plaza. "Most people I show houses to don't balk at the commute because it's down Route 4 [Pennsylvania Avenue], and that is the least congested of the routes into the District."