The Harbors at Haverstraw residential complex is being built in Rockland County. About 15,000 units of housing are under review or being constructed along the Hudson River.

First came the gracious estates and summer getaways of the 1800's, built for New York City businessmen who yearned for Hudson River breezes and Palisades views. Then came decades of suburban-style home building, with colonial- and Tudor-style set back in hills and valleys while heavy industry and noisy trains came to dominate the riverbanks.

But now another housing boom is unfolding along the Hudson. From Yonkers to Kingston, thousands of units of town houses and apartments to buy or rent are planned for the river's edge, where manufacturing has long been in decline.

A confluence of forces - a cleaner river, empty lots created by vanished factories, a housing boom, the proliferation of suburban developers, a willingness by local officials to embrace a new source of tax revenues, and a crystallizing Hudson Valley consciousness - have come together in recent years to generate interest in building and living along the Hudson.

Almost all of the planned housing falls in the luxury category, with condominiums costing as much as a four-bedroom house inland. With it will come the amenities of a rejuvenated Hudson River, with docks, riverside dining and parkland.

The plans are not universally popular. Vehement antidevelopment efforts extend up and down the Hudson, with environmentalists and river enthusiasts joining forces to try to rein in the projects. But most of the battles are over scale, riverfront access and affordability. And it is becoming increasingly clear: The next great phase for the Hudson River is housing.

Some of the proposals are so ambitious that they would create villages within villages, leading to population increases and, some critics charge, a total change in the character of the towns. Several smaller projects are in the works as well; some have recently opened.

Sleepy Hollow, in Westchester County, is considering a plan for 1,250 units of housing on a 100-acre site where General Motors once assembled cars that affords stunning views of the Tappan Zee Bridge.

Across the river in Rockland County, construction has begun on the first of 850 units in Haverstraw, a former brick-making center.

In historic Kingston, the first state capital, in Ulster County, a developer wants to transform an abandoned cement plant into 2,182 rental and condominium apartments and town houses.

Altogether, there are about 15,000 units of housing now under review or being constructed along the river, according to an estimate by Scenic Hudson, an environmental organization. Scenic Hudson has formed a coalition with several groups to oppose the Kingston plan.

Elected officials have raised concerns about the density of the plans, but have, for the most part, embraced them, particularly in communities that have felt the sting of departing industries.

"There are two things we can do," said James M. Sottile, the mayor of Kingston, which has lost a fifth of its population since the 1960's. "We can grow our tax base or we can grow our tax rate. We're going to develop here in the City of Kingston, and we're going to do it responsibly."

But some of the same groups that helped defeat a proposal this year for a huge new cement plant in Columbia County have now shifted their attention to what they call the new megaprojects. They say the developments will introduce sprawl to the banks of the Hudson, with its implications for traffic, visual blight and pollution runoff.

They also fear the upscale nature of most of the proposed housing, saying the developments will stand apart in areas like Sleepy Hollow, Haverstraw, Kingston and Yonkers, which are mostly blue collar and ethnically and racially diverse.

"These megaprojects threaten to damage the ecology and world-class vistas that make this a tourist destination and a great place to live," said Ned Sullivan, Scenic Hudson's president.

"It's critical that citizens come together and share their vision of what the waterfront should be like rather than have elected officials turn it over to developers whose sole motive is to make a profit," he said.

Early in the 19th century, the banks of the Hudson were ideal for building homes, until the addition of railroad lines kept builders away.

Washington Irving, author of "The Legend of Sleepy Hollow" and "Rip Van Winkle," built his home, Sunnyside, now a historic landmark, just feet from the river in Tarrytown. Irving, a former envoy to Spain with political connections, tried to prevent the railroad from slicing across his placid retreat, as did his neighbors, but to no avail.