This land is still your land, pretty much the way it was for most Americans in 1940 when Woody Guthrie immortalized the gamut of the United States, from California to the New York Island and all the redwood forests, diamond deserts, wheat fields and golden valleys in between.
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Times Topic: Census Bureau
Except for one thing: There’s less of it. Officially, the nation’s land mass has been shrinking almost steadily ever since 1940.
According to the Census Bureau, the land area peaked that year at 3,554,608 square miles. By 1990, it had declined to 3,536,278 square miles. In 2000, a slight increase was recorded of about 1,200 square miles. But since then, the bureau estimates, this land has shrunk by about 5,500 square miles (a larger area than Connecticut and five times the size of Rhode Island), to 3,531,905.
Not to worry, though, the nation’s geographers say. Most of the decline is a result of improved satellite imagery and other mapping technology that can better distinguish land from water (like the gulf stream that Guthrie also glorified) and of more precise definitions of what constitutes each.
Still, government experts acknowledge, some of the decline may have resulted from erosion, hurricane damage and rising sea levels.
Since 2000, the nation’s official measurement of its territorial waters rose to 264,837 square miles from 256,645, an increase of more than the surface area of Lake Ontario.
Some of the biggest land-to-water shifts in the last decade were recorded in Louisiana, which suffered severe flooding and erosion from Hurricane Katrina in 2005, but which also expands its land area periodically from silt deposited by the Mississippi River. Since 2000, according to the official count, the state’s land area decreased by more than 350 square miles. Water area grew by more than 500 square miles.
In New York, the Borough of Queens shrank by one square mile in the decade, possibly a result, in part, of erosion and rising sea levels in the Jamaica Bay unit of the Gateway National Recreation Area. The Army Corps of Engineers is trying to stem the tide there by restoring salt marshes.
If anything, the Census Bureau acknowledges, land area may actually be overstated.
“For area measurement purposes, hydrologic features identified as intermittent water, glacier, or swamp are reported as land area,” it says, adding this cautionary note: “Identification of land and inland, coastal, territorial, and Great Lakes waters is for data presentation purposes only and does not necessarily reflect their legal definitions.”
With land and water combined, the country actually grew to a record 3,796,742 square miles, from 3,794,084 in 2000.
“Our total area didn’t change very much, but we added a lot of internal water to our database,” said Jennifer Holland, a Census Bureau geographer. “It’s possible some results from beach erosion and rising sea levels, but mostly it has to do with us getting better boundaries.”
The revisions, completed in 2008 in conjunction with the National Hydrography Datasetby the U.S. Geological Survey, have remained constant since then for the country over all, with slight variations. The Missouri River’s shifting course, for example, altered the land mass of Nebraska and Missouri.
Data for Texas was collected in a drought year, another variable.
C. M. Trautwein, a geologist with the survey’s Earth Resources Observation and Science Center, explained that “the more accurate means of mapping water bodies and land-water” of the past decade are, in part, responsible for the differences.
But exactly how much, he acknowledged, “is difficult to say.”
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