Residents of Oxon Hill, worried last year about their prospective new neighbor, posted the handmade signs in their yards for months: "What is National Harbor?"

The $2 billion development on the Prince George's County banks of the Potomac River, scheduled to open its first phase in 2008, was described by proponents as a "waterfront entertainment venue." State legislators mentioned it as a possible site for slot machines. Residents feared Disney-on-the-Potomac or Atlantic City II.

That picture changed dramatically late last month, when the County Council approved a request by the developer, Milton Peterson, to add 2,500 high-end condominiums and townhouses -- with prices as high as a half-million dollars -- to the projected mix of office and convention space, retail and restaurants.

Peterson has argued that to attract the top-tier restaurants and stores county residents have long sought, housing must be a part of the project's mix. He was also eager to take advantage of a hot housing market.

But the change in plans is also a political statement by Prince George's leaders, who have long sought to end what they consider the county's role as a magnet for cheap garden apartments and cookie-cutter townhouses. Beginning with former county executive Wayne K. Curry (D), Prince George's has pushed for more estate-type housing and mixed-use projects, particularly near Metro stations.

Buoyed by a regional construction boom, Curry's vision has started to materialize. Several other large-scale, mixed-use projects in the county are in various stages of development: Konterra in Laurel, at the northern tip of Prince George's near Montgomery County; Karington and Woodmore Town Centre, near Bowie; and the Mall at Prince George's, near the Hyattsville Metro station. Each development has attracted nationally prominent builders who have never done business in the county before.

Although market forces have played a big role, county leaders said the new developments also reflect a coming of age for Prince George's.

"I think it's a reflection of the county's maturation," said Kwasi Holman, the county's economic development director.

"It's another step in our evolution from rural to suburban to urban," said former council member Peter A. Shapiro, a fellow at the University of Maryland. "In essence, what National Harbor will become is one of the truly urban places in the county. . . . It's classic 'new urbanist' development pattern, the direction that most major development is going in around the region."

Council Chairman Samuel H. Dean (D-Mitchellville) said the county "has become the crown jewel for housing and mixed-use. It's what everybody wants, and the builders are selling them as fast as they build them."

Dean supports National Harbor and was an initial sponsor of the legislation to add housing. But this summer, he pulled the measure from the council agenda when the bill was scheduled for final action. Sources said Dean wanted more minority participation and equity in the project. But Dean denied that it was the main reason. Instead, he said, he wanted to make sure that residents supported the change.

Shortly after his election in 1994, Curry sent a message to developers that he was tired of Prince George's serving as what he called a dumping ground for low-end housing. It was a legacy of the 1960s, he said, as whites leaving the District settled in garden apartments clustered mostly inside the Capital Beltway. In the 1970s and '80s, as tenants began to buy their first houses, developers built low-cost homes. Townhouses followed.

Zoning for the National Harbor site originally allowed residential construction, and Peterson incorporated it into his 1997 plans. But Curry discouraged it and pushed the council to change the zoning to preclude homes. The concern was that the result would be an assemblage of $150,000 homes along the Potomac.

"I think there was a perception years ago that that was what it would be," said County Executive Jack B. Johnson (D), who supported Curry's push for better-quality housing.

That no longer is the case, he said.

"Now, you can't find $150,000 homes in the county anymore."

Oxon Hill residents who had been staunch opponents of National Harbor support the addition of housing. They regard it as a hedge against the project becoming too much of a disruption. People buying half-million dollar homes, they reason, are going to want the same quality of life as their neighbors.

"We didn't want Orlando, and we didn't want Atlantic City," said Donna Edwards, who said that housing fits in with the community's effort to extend a proposed Metro Purple Line across the Woodrow Wilson Memorial Bridge.

"We're working very hard with the community and with Peterson to bring rail across the bridge with a stop at National Harbor and a stop at downtown Oxon Hill," said Bonnie Bick, who once posted a sign in front of her home questioning the project.

Last summer, Bick and Edwards's group, the Campaign to Reinvest in Oxon Hill, dropped its lawsuit against Peterson after reaching an agreement that required the developer, among other things, to set aside a specific portion of the site for housing.

"I always thought it was a mistake," Edwards said of Peterson's initial plans to exclude housing. "True mixed-use includes residential. . . . It needs it to be successful."