Check the pulse of housing industry observers and you'll find them positively giddy about the prospects for new-home construction at the dawn of the 21st century. Growth in the U.S. population, along with shifts in where that growth is coming from, will be the major factor in keeping demand for new housing brisk.

During the first two decades of the next century, the U.S. population is projected to grow by an average of 2.4 million people per year. That translates into 1.1 million to 1.2 million new households annually, according to a National Association of Realtors study titled "Housing in the New Millennium." Some of those new homeowners will buy existing housing stock, but many will be in the market for new houses.

Industry watchers continue to credit the baby boomers with inspiring new and different types of housing as they age and their lifestyles change. Consider that as of this year, more than 30 million boomers will have reached their 50s. By 2010, that number will surpass 40 million.

The good news for residential architects is that this age group also happens to span the peak custom-home­buying cohort of 45 to 64, as defined by the National Association of Home Builders. The possibilities for work seem almost boundless. One example: Second-home construction alone should boost housing starts by 100,000 to 150,000 units each year through 2020, says NAR spokesman Walter Molony.

Immigration will fuel about 25 percent of the growth in household numbers in the next decade, according to Harvard University's 1999 report "The State of the Nation's Housing." But a much greater portion--65 percent--will come from young Americans maturing into heads of households.

Echo boomers--composed primarily of the 84 million U.S.-born children of the baby boomers--are already beginning to reverse the recent decline in the young-adult population, adding an average of 20,000 each year to the ranks of 18- to 24-year-olds. By 2010, they'll account for more than one in 10 homeowners and four in 10 renters.

And the oft-forgotten parents of baby boomers, many of whom are now in their late 70s, 80s, and 90s, will make waves of their own. Because most of these seniors live in conventional housing and prefer to stay put, they will create a great demand for housing modifications to help them deal with the infirmities of aging, says the Harvard report.

While the number of American households continues to increase, the average size of families in the United States has diminished by 20 percent in the three decades since 1970, says Gopal Ahluwalia, NAHB's director of research. What's important for architects to know, however, is that this downsized family is demanding larger homes: Over the same three decades, the size of the average American home has increased in square footage by a whopping 49 percent--up from 1,500 square feet in 1970 to 2,230 square feet by mid-1999, says Ahluwalia.

Several characteristics of the American home are changing along with size, Ahluwalia notes. For instance, while the open kitchen/family room configuration remains very popular, "the living room is a vanishing breed," Ahluwalia says. "In the next 10 years, the living room will disappear, because the family room is becoming larger and more prominent."

Likewise, the ubiquitous television has left the living room and moved to the media room. Four bedrooms and two-car garages--once the domain of homes belonging to business owners, professionals, and corporate managers--are now standard fare for American homeowners across the board, says Ahluwalia. "The next wave is technology--multiple telephone lines, whole-house wiring, central music systems, and lighting controls. These are the things that are going to come next."