As environmentalists, school children and others celebrated Earth Day this week, one group looked at a measure of urban sprawl and "vanishing open spaces."
The report, which is done once every decade by the Numbers USA Education and Research Foundation, concluded that the nation is not doing very well on conservation of our land resources.
Crunching the numbers, the foundation found that in the last decade, an area larger than the entire state of Maryland — more than 13,000 square miles of farmland, woodlands and other natural habitat at the edges of our cities — were cleared, scraped, filled, paved and built over to handle the expanding population and growing appetite for more developed land.
As with the foundation's previous studies, this one relied mostly on data from the U.S. Bureau of Census and U.S. Department of Agriculture.
The Natural Resources Conservation Service (NRCS) has noted that more than one-third of all the open spaces that have ever been converted to development in this country's history were eliminated from natural use and agriculture in just the last 25 years.
"The good news during the last decade was that the galloping hyper-sprawl of the 1990s calmed significantly," the report noted.
"The primary reason was that the rate of per-capita land consumption stopped increasing as rapidly as it had over much of the post-World War II era. Indeed, by one measure, the average urban resident increased his or her amount of urbanized land by a relatively modest three percent."
However, that lower growth rate still combined with a continuation of the largest numerical population growth in U.S. history to drive open-space destruction at a higher volume than any time other than the 1990s, the report's authors concluded.
"While the country obviously can survive the recent losses, the report questions how long these trends of destruction can continue," said Roy Beck, co-author of the report that is titled "Vanishing Open Spaces: How an Exploding U.S. Population is Devouring the Land that Feeds and Nourishes Us."
The report spotlights cropland as what it called a "particularly frightening" example of unsustainable rates of loss. In the early 1980s when the NRCS began its major land surveys, the country had 1.9 acres of cropland for every American.
By 2010, that had declined to 1.2 acres. If the 30-year trend of high population growth and massive land development continues, there would be only 0.7 acre of cropland per American in 2050 and only 0.3 acre in 2100, the report states.
This study finds that around 70 percent of the land losses around urbanized areas over the last decade were related to the nation's continuing trend of high population growth and the need for places to house people.
Of the 497 urbanized areas in the study, a number from Wisconsin were named.
Milwaukee ranked 57th (one was the worst) with sprawl of 59 square miles; Madison was 94th with sprawl of 37 square miles.
Nationally the farmland and natural habitat that was taken over for urban development totaled 13,586 square miles or 8.3 million acres.
On a state-by-state basis Texas had the top ranking with 1,572 square miles; Florida ranked second with 853 square miles and California was third.
In the state rankings Wisconsin came in 16th and had moved closer to the top in terms of sprawl, from the previous survey when it was ranked 19th.
The foundation also surveyed Americans on their attitudes toward conservation and protection of open lands. They found 92 percent said it is important to protect farmland from development to ensure the ability to feed people into the future.
Seventy-one percent of those surveyed said it was "very important" to protect farmland.
The survey found that by a three-to-one margin Americans think it is "unethical" to pave over good cropland to use for housing a growing population rather than it being a legitimate use of land.
The study found that the majority of Americans feel a spiritual or emotional uplift from time spent in natural areas. Eighty-five percent said it is important to them to be able to get to natural areas fairly quickly from where they live.
That same margin, 85 percent, said the loss of 17 million acres of woodlands over the last three decades is a significant problem for wildlife.
The national poll was conducted in April by Pulse Opinion Research for the foundation.
Study co-author Roy Beck is also executive director of Numbers USA, and is an outspoken advocate of limiting immigration into the United States as a way to control the population.
Other Wisconsin urbanized areas that were ranked by the study included:
■ Green Bay ranked in 157th place for its development of 22.9 square miles from 2000-2010;
■ West Bend ranked 203rd in the study based on the development of 15.2 square miles;
■ Eau Claire was ranked 251 based on the development of 11.5 square miles;
■ La Crosse ranked 258 in the nation for the development of 10.6 square miles;
■ Wausau ranked 273 among the communities in the study for developing almost 10 square miles from 2000-2010;
■ Kenosha was ranked 283 for development of 9.1 square miles;
■ Sheboygan ranked 307th for the development of 7.7 square miles;
■ Oshkosh was 369 in the rankings with development of 4.2 square miles;
■ Racine was ranked at 384th place with development of 3.6 square miles;
■ Among Wisconsin's urbanized areas Janesville had the least sprawl in the survey with the community coming in at a rank of 420th and development of only 1.4 square miles over the most recent 10-year period covered by the survey.