Every day, more people come into this world than leave it. I suppose it's always been this way. But now, the accumulation of millennia is really starting to show. Last year, the population of the planet surpassed 6 billion human beings, with no signs of slowing down.

Admittedly, some countries are experiencing almost no increase in population, notably Japan, Italy, Belgium and Spain to name a few. With low birth rates and limited immigration, they face a long-term drop in population. Meanwhile the rest of the world continues to show a lusty proclivity to fertility.

In the U.S., the current population of 275 million people is expected to balloon to almost 350 million by 2030. The U.S. will grow by nearly the equivalent of Germany in only 30 years. The state of California's population will hit 52 million -- not far from that of England.

The impact of all these people is seen everywhere. I grew up in semi-rural Michigan and vividly remember how you didn't have to drive too far out of town before you saw cows and corn fields. But what used to be farmland, orchards and fields are now 5-lane roadways, mega-malls, strip malls and movie theaters. You have to drive nearly 20 miles to find what are now the rural fringes. And every year a new ring of subdivisions pushes that boundary out farther.Worse still, the traffic is becoming horrendous. The aver age U.S. motorist now spends 80 minutes driving a day. In some particularly dense areas it's more like 180 minutes. Growth and congestion are making the automobile less and less of an efficient way to get around. Yet, the auto industry doesn't seem too worried that the system its products use is clogging up.

Maybe that's because automobiles are amazingly well developed machines. They are nearly 98% cleaner than they were before emission standards. Over that same time period, the rate of highway accidents has been cut in half. But we're not likely to see that rate of improvement maintained. All the easy stuff has been done.

We can now get more reductions in emissions and better improvements in fuel economy by better managing traffic congestion. This requires a better overall system, not just better cars. Let's face it, there isn't much of a system out there. Every morning the world wakes up and puts half a billion vehicles on its roads. With the exception of some stop signs and traffic lights, we pretty much say to motorists, "Hey, you figure it out." And yet we have access to technology that could provide some immediate impact in the short term.

Intelligent semaphores, for example, could sense how many cars are approaching an intersection and give the green light to the heaviest flow of traffic. Better still, if no traffic was coming in one direction, these lights would never stop the cars coming in the other direction. How many times have you been held up at a red light at an intersection along with other cars, with no traffic coming the other way? You sit there, idling, wasting time and gasoline.

Real-time route guidance is another available technology that could reduce congestion. This combines navigation with a real-time traffic monitoring system. It alerts motorists of traffic jams up ahead and provides them with alternate routes.

In the long term, self-driving vehicles that allow platoons of cars to travel down the highway safely, running bumper-to-bumper, would help increase the traffic density that roads can handle. And presumably these cars could take us to the curbside of our destination, drop us off, then go find a parking spot on their own.

Many argue in favor of mass transit to reduce traffic congestion. There's no question it can play an important role, but it brings some problems, too. For one thing, mass transit, such as trains and subways, requires very costly infrastructure investment. Plus, it doesn't persuade people to stop buying cars. Japan arguably has the best mass transit system in the world. You can get just about anywhere without a car. Yet Japan is the second largest car market in the world. First chance they get, people love to buy their own set of wheels.

When you mix people's love of cars with a burgeoning planetary population, you get congestion. The rampant growth we see is increasingly coming under attack from anti-growth partisans. They deplore crass commercialism, tacky architecture and environmental degradation that so often accompany this growth. I pretty much agree with their observations, but as long as the population continues to grow, it's unrealistic to think that you can stop development.

But allowing it to grow helter-skelter is slowly choking off the efficiency of the automobile. We would do ourselves a favor to recognize that its long-term viability will one day be threatened unless we start to devote more of our energy toward building a better system in which our cars operate.