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Following are brief excerpts from selected observers. Links to all six observers' articles are provied below.

"I have seen the future . . . and it is hard-topped and held up in traffic. Tomorrowland is neither free nor mobile. Twenty-five years from now, as the number of cars equals or exceeds the population of everyone over 15, Americans face congestion from sea to shining sea -- or from shore to flooded..."

-- Jane Holtz Kay, author of "Asphalt Nation" and planning critic for the Nation magazine.

"Our Washington area of 2030 is so much smaller than that of 2005 that it is sometimes hard to understand how our ancestors made such laughably wrong growth projections 25 years ago. They ignored three vital forces: the rising water, advances in communications technology and the crumbling of the federal government."

-- Joel Garreau, Washington Post editor and reporter, and author of books on U.S. social change and edge cities.

"One question naturally arises when you hear that 67 million more people are on the way: Do we have enough to go around? Last year raised worries about "peak oil," the notion that the glass of crude may be half empty, bringing with it higher prices, increased jousting with countries like China, maybe even threats to the supremacy of the sprawled-out American suburb. Now get ready for peak water, and even peak food."

-- Bill McKibben, environmentalist and author, whose most recent book is titled "Wandering Home."

"For most of the 20th century, the year for long-range urban planning was 2020. We called it the "perfect vision" year. Now we are asked to look forward another decade. Within the new time frame, architects will still, surely, look ahead, proclaiming the House of the Future, or the Ville Contemporaine as Le Corbusier did in the 1920s, or the New Urbanism as they do today. But their prophesies will be no more perfect than the previous ones, continuing to tell us more about their own time than about 2030, because cities rarely arise from visions."

-- Denise Scott Brown, architect, planner and a principal in the firm Venturi, Scott Brown and Associates