horror vacui

Nature abhors a vacuum said Aristotle. The reality is that nature may not care so much, but people certainly do. And when there are big spaces to fill, more people appear. In 1950, the US had 150 inhabitants. By 1970 there were over 200 million. In the early 90's we crossed 250 million, and somewhere earlier this year 300 million. There are twice as many people in the country now than in 1950. Even so, compared to China and India, the numbers are tiny. But US inhabitants are richer and their impact is far larger.

We have a strong desire to fill the space around us with objects. One very common object is a house. In 1950, there were roughly 46 million homes. Today there are 116 million. More than a quarter of Nevada's home were built in the last 10 years. We are in runaway mode when it comes to building. Maybe the subprime crisis will put a stop to it.

Not only do we have more houses, these houses are getting bigger too. According to the National Association of Home Builders, the average square footage of an American house has been rising from 983 sq ft. in 1950 to over 2,350 sq ft. today. Assuming 116 million units, that means almost 10,000 sq miles of land is in houses. That is an area almost the size of Haiti.

And with a nice house comes a nice lawn. The current estimate is that more surface area in the US is devoted to lawns than to any other irrigated plant. Lawns cover more than three times the acres of irrigated corn. According to Dr. Milesi at NASA, there are nearly 50,000 sq. miles of lawn in the US. There are enough lawns in the US to cover Nicaragua or Greece. 

Lawn distribution in the US can be seen on the NASA earth observatory web site. There you can see that people sport lawns irrespective of where they live. Some of the driest areas in the country have as many lawns as Florida.

Water is a very precious resource in the US. The continent is rather dry. And those lawns, if irrigated properly require 200 gallons of fresh water per person per day, according to Dr. Milesi. But many people use more water than that. Better safe than sorry. Irrigation is the leading water use in the country at 134 billion gallons per day. 

To put things in perspective, Americans flush 6.8 billion gallons of water down their toilets. The estimated average daily household water use is 350 gallons according to the American Water Works Association.

And water is not the only resource we consume. To fill the vacuum, we drive all over it. In 1972, 80% of households had one car. Today 88% have at least one. The average is two. In 1960, there were nearly 62 thousand passenger cars. In 2002, we had 136 thousand. Those cars traveled 587 million miles in 1960 for an average of 9.5 thousand miles per vehicle. In 2002, the average is 12.2 thousand miles per vehicle per year, for a total of 1.7 billion miles. That is more than 3,500 trips to the moon and back.

We all know that cars are more efficient now, with the average mpg going from 14.3 in 1960 to 22.1 today. Nonetheless fuel consumption almost doubled from 41 billion gallons to 75 billion. The total amount of fuel used by all vehicles rose from 58 billion to 168 billion gallons according to the US Dept. of Transportation. The California Energy Commission puts the average fuel use per person per year at 464 gallons in 2004. That adds up to 139 billion gallons.

Whatever our fear of vacuum may be, we are certainly working hard to cover it. And in doing so we are emptying our fuel and water supplies faster than anyone can imagine.