The winter 1999 issue of Housing Facts & Findings caught my attention last month with an article headlined, "The American Metropolis at Century's End: Past and Future Influences." The Fannie Mae Foundation, the publication's publisher, had asked 149 urban scholars to select the top 10 influences on cities during the past 50 years and then to predict the 10 most likely influences of the next 50 years.

The foundation sent a survey, listing an array of possible influences, to members of the Society for American City and Regional Planning History, an interdisciplinary professional organization of urban historians and social scientists, planning educators, practicing planners and architects.

The results, reported in the article by Robert Fishman, a professor of history at Rutgers University-Camden, speak for themselves, although you may find some of them surprising. The Top 10 influences, ranked in order of importance as measured by frequency of responses, were:

1. The 1956 Interstate Highway Act and the dominance of the automobile.

2. Federal Housing Administration mortgage financing and subdivision regulation.

3. De-industrialization of central cities.

4. Urban renewal--downtown redevelopment and public housing projects (1949 Housing Act).

5. Levittown (the mass-produced suburban tract house).

6. Racial segregation and job discrimination in cities and suburbs.

7. Enclosed shopping malls.

8. Sun Belt-style sprawl.

9. Air conditioning.

10. Urban riots of the 1960s.

Several items on the list are closely linked, such as enclosed shopping malls and air conditioning, the former impossible without the latter. But all share a common thread: Each caused, enabled or symbolized the growth of suburbia. Federally funded highways, affordable mass-produced cars and houses, federally insured mortgage financing and cheap land were an indispensable combination. Together they facilitated de-industrialization of cities, eliminating job opportunities for minority urban populations unable to leave the city.

"The single most important message of the list of past influences," writes Fishman, "is the overwhelming impact of the federal government . . . through policies that intentionally or unintentionally promoted suburbanization and sprawl."

And while most of the influences cited are linked directly to social and economic conditions, all have had profound physical effects on both built and natural environments. These influences shaped citizens' behavior and attitudes, but they also gave three-dimensional shape, for better or worse, to American cities and surrounding landscapes.

Notably absent from the list of influences are urban design theories, construction technology, mass transit, cheap gasoline, tax policies, cultural amenities, urban public education or quality of municipal government leadership.

Now consider the foundation's 10 most likely influences for the next 50 years," again ranked in order of importance.

1. Growing disparities of wealth.

2. Suburban political majority.

3. Aging of the baby boomers.

4. Perpetual "underclass" in central cities and inner-ring suburbs.

5. "Smart growth," or environmental and planning initiatives to limit sprawl.

6. The Internet.

7. Deterioration of the "first-ring" post-1945 suburbs.

8. Shrinking household size.

9. Expanded superhighway system of "outer beltways" to serve new edge cities.

10. Racial integration as part of the increasing diversity in cities and suburbs.

This is a quite different list. Several items are contradictory or suggest opposing trends, such as items 1 and 4 in contrast to item 10, or item 5 in contrast to items 7 and 9. Recognizing America's rapidly growing elderly population, items 3 and 8 suggest that types of housing and residential communities needed in the future will differ substantially from today's norm.

"Smart growth" optimism is fueled by hopes that voters, increasingly concerned about the environment, unbridled growth and worsening traffic congestion, will eventually demand and support sound planning of the sort undertaken by states such as Maryland and cities such as Portland, Ore. Optimists predict that the inner-ring suburbs may not deteriorate, that future generations will stop gobbling up the distant countryside and choose instead to live together in harmony, inhabiting revitalized cities and older suburbs.

Pessimism is fueled by increasing signs of divisiveness and forces of separation in society--gated communities, shrinking supplies of affordable housing, dramatic personal income differentials and failing city school systems. Pessimists doubt that Americans in the next half-century will embrace social, economic and ethnic diversity and integration. They foresee trouble-plagued inner cities not only continuing, but encompassing more neighborhoods.

Who's right? Probably both predictions will prove somewhat correct.

The political impetus for smart growth will strengthen. Regulation of land use and resource preservation will intensify. People will choose to live in cities because of convenience, culture, diversity and dynamism of urban life.

Nevertheless, many Americans will continue to shun city life, opting for what they perceive to be the advantages of life in the hinterland, life with others just like them, life unencumbered by urban problems.

And what about that pesky future influence number 6, the Internet?

Fishman notes that the Internet today may be like other inventions whose impact could not be foreseen. When the automobile came along, who could imagine a Los Angeles or a 12-lane freeway? "While railroads tended to favor the big cities and highways favored the suburbs, the Internet can potentially spur economic development on the most remote mountainside, in the densest downtown, and anywhere in between."

Ironically, the Internet's biggest impact could be on automobiles and traffic--we may need to use cars much less.

Meanwhile, always the optimist, I'm betting that cities as we know them still will be with us. And I intend to continue living in one.

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