As much as urban planners might wish that the personal automobile would disappear from America's streets and highways, that is not likely to happen in the foreseeable future. But, if automotive research and development goes according to technical, financial, and political plan, very few vehicles powered by internal-combustion engines burning fossil fuels will remain in use twenty-five years from now. Hybrid, all-electric, and fuel-cell vehicles will dominate the highways in 2034. All of this will have been made possible because the infrastructure necessary to support them was built. Gas stations will have been converted to dispense a variety of nonfossil fuels—including hydrogen—and parking meters will have been equipped to serve as battery-recharging hitching posts. The few internal-combustion vehicles that do remain on the road will be burning biofuels or compressed natural gas.

This is the good news, but it does not come without some bad. Already, the decline in fossil-fuel use has resulted in a decline in tax revenue intended to fund highway maintenance projects. So far, alternative fuels have been largely subsidized, but creative new means of green taxation will likely accompany the rise in use of clean energy sources in the coming decades. By 2034, older bridges will have been replaced, many with structures that use form and color to add an artistic flair to their engineering. There will be so many notable pieces of highly visible infrastructure that they will have made our constructed landscape into one grand outdoor sculpture garden.

Because automobiles and trucks will be generally smaller and lighter, roads and bridges will deteriorate at a much slower rate. Most interstate highways will have been retrofitted with so-called smart pavements, which not only will heal themselves of cracks and potholes but also will interact with smart vehicles to keep them automatically in their lanes and at safe distances from each other. Driver intervention will be necessary only when changing lanes and entering or exiting the highway. Bridges, tunnels, and other critical structures will also be smart, giving warning of any impending failure.

There will be free ultra-high-speed wireless Internet access available from any car on any road anywhere in the country. We can speculate about the scenery through which those cars will be driving: Farmland along our highways will be interspersed with clusters of wind turbines hundreds of feet tall, situated to take advantage of prevailing winds and to feed the power generated directly into the national grid. Some farmland and much desert will be given over to vast fields of solar-power plants. The roofs of energy-self-sufficient buildings will be fitted with small-scale wind turbines and solar panels. Many of the vehicles on the road will also have solar panels built into their roofs.

Since so many vehicles will be powered by electricity, city streets will be pollution-free, and concerns over global warming will have been allayed. There will be no smog, and people will breathe freely. Busy streets will be as quiet as a country lane because cars and trucks will emit no noise above a barely audible hum. Since this means that blind people may not hear vehicles approaching intersections, vehicles will be equipped with warning devices that will emit constantly changing soft electronic tones that indicate traffic conditions in the street.

Infrastructure comprises not only roads and bridges and intersections, of course. The American Society of Civil Engineers occasionally issues report cards on some fifteen categories of the built environment—ranging from airports to wastewater-treatment plants—that it grades on the basis of condition, performance, capacity, and other criteria. On the latest report card, nothing received a grade higher than C+, and the nation's overall infrastructure grade-point average was equivalent to a D, which was defined as "poor."

Reviving such concepts as a Civilian Conservation Corps and a Works Progress Administration could go a long way toward reclaiming, improving, and supplementing aging roads, pipelines, and other essential networks with bold new projects. But our future physical infrastructure will only earn respectable grades if efforts to rebuild the existing one are based upon a financial system sound enough to continue to fund and maintain them properly. Ultimately, then, what physical America looks like in 2034 will depend as much on financial conditions, public policy, politics, and political will as it will on engineering and technology.

Petroski has written fourteen books on engineering and design, including The Toothpick: Technology and Culture, published in 2007.