What has been the biggest influence on architecture in the 20th century? The answer depends on your perspective.

Some architects, or architectural aficionados, might say "computer-aided design," "new materials," "the invention of the curtain wall" or an "awakened sense of history."

Personally, I would argue for "context"--people have at last become sensitive to the importance of relating projects to the environment in which they are built.

But most homeowners would likely have a different answer. After some reflection about the buildings where they live, they might answer "machines."

Architecturally, today's houses are not that different from houses built 100 years ago, except that they may not be as well constructed. Two-by-fours really aren't two inches by four inches. Siding and shutters are likely to be vinyl, not wood. Slate or wood roofing shingles were long ago replaced by asphalt shingles, copper flashing by aluminum flashing, plaster by drywall, metal pipe by plastic pipe and true divided-light windows by windows with snap-in mullions.

Glazing, sealants, insulation and paints have been greatly improved over the past 100 years, but these have had relatively little impact on domestic architecture.

Typically, houses at the close of the 20th century, constructed with 20th century materials to accommodate 20th century living patterns, look vaguely like houses built in the 18th or 19th centuries. Family rooms, kitchens, bathrooms, master bedrooms and closets have grown as living and dining rooms have shrunk. Yet the most dramatic change is not the basic architecture of homes. It is the machines that fill them.

The inventory of modern domestic machines is impressive: garage door openers; garbage disposers, dishwashers, refrigerators and ice makers; microwave ovens, washers and dryers; heating and air-conditioning systems; electronic filters and humidifiers; intelligent thermostats, burglar alarms, programmable lighting and built-in communication; and entertainment infrastructure.

Of course, the 20th century machine that arguably has had the biggest impact on residential architecture is the automobile. Two- and three-car garages now make up a substantial piece of many houses, and garage doors are commonly the most dominant openings in facades facing subdivision streets.

The century's most aesthetically influential and emblematic machine, the automobile has changed not only how we design homes, but how we design cities, suburban communities, commercial centers and every other kind of development. When consumers leave home for almost any destination, they are much more likely to be concerned about parking than about context or architectural form.

Will context and cars be the dominant design forces during the next century?

Some futurists believe that information technology and the Internet, not cars and context, will be the most powerful determinants shaping inhabited environments in coming decades. A few predict that cyberspace, not physical space, will consume most of humanity's design thinking during the next millennium. With everyone hyperlinked day and night, no matter where they are, who needs transportation or a room in which to sit and talk? Three-dimensional environments will be of little import, if not obsolete.

Don't hold your breath. Notwithstanding the relentless ebb and flow of stylistic trends, fundamentally little will change in the world of architecture, especially residential architecture. For a long time to come, most Americans are likely to continue caring about context while driving cars to and from homes with garages in which to park them.

Roger Lewis is a practicing architect and a professor of architecture at the University of Maryland.