When I first got my driver's license back in 1978, the freeways in Los Angeles were practically deserted at night - a perfect test bed for a teenager figuring out how fast Mom’s car could go.

I could flout the speed limit because the population density in LA was just 6,366 people per square mile. And, in the San Fernando Valley suburbs of my childhood, I suspect it was much lower. Everything shut down at 10 PM in the Valley because there weren't enough people to keep the nightlife humming.

25 years later, the population of the United States has topped 300 million,

and the population density in LA is 8006 per square mile - an increase of more than 30%. The freeways are jammed at all hours.

All this has me wondering: Is the U.S. over-crowded? Do we have room to keep growing?

Those questions have gotten a lot of attention lately, now that the population has topped 300 million. I found some of the recent reporting on population density in the U.S. a bit misleading. By comparison to Germany, the U.S. seems almost empty. The Germans pack in 598 people per square mile, while we get by with just 82. Montana alone is about the size of Germany and is empty: 6 people per square mile.

There are a lot of wide open spaces in the U.S., but not many people want to live in the Mojave Desert. And, it's awfully cold in Northern Montana. Like most other countries, Americans crowd along the coastline. The center of the country is, in fact, depopulating.

And for a very good reason, says Carl Haub of the Population Reference Bureau, "No one is going to live in western Nebraska. There are no jobs."

So what about the coasts? There, America looks far more crowded. California has 217 people per square mile and is adding 10 million people every year. If California keeps growing, in 20 years it will have the same average population density as China. Though, the Golden State will still be well below comparably sized Vietnam and its 652 people per square mile.

Congestion shows up in many ways in California and other coastal states: high home prices, rising rents and water bills, not enough land for developers. But the most dramatic stat is the amount of time Americans are spending on the road. A recent report indicates one of the fastest growing segments of commuters hits the road at 5 AM to beat the traffic. The Texas Transportation Institute now says 51 metro areas are congested, compared to five in 1982. Today's rush hour travelers are tied up in traffic for 47 hours - more than two and a half times the time spent in traffic 25 years ago.

But is density all bad? I don't think so. The San Fernando Valley I grew up in had lots of space, but nothing to do. There were a few book stores, not many restaurants, and. . .you get the idea. That's all changed now. As population densities rise, a city or suburb is able to support a wider array of businesses and services. Simply put, there is much more life in the San Fernando Valley now.

Where's the limit to growth in this country? The best place to get the answer may be New Jersey. It is the most crowded state in the nation with 1134 people per square mile. By comparison, China's most populous province, Guangdong, has 1606 people per square mile.

Is the U.S. over crowded? If you want empty freeways and quick commutes, yes. If you like interesting cities and lots to do at night, no.