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The Unlost Art: Topo Maps
Bil Gilbert
November 25, 1974
Replacing the hearsay of hunters and trappers, they helped open up a continent and today are stimulating, even witty, company on the trail
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November 25, 1974

The Unlost Art: Topo Maps

Replacing the hearsay of hunters and trappers, they helped open up a continent and today are stimulating, even witty, company on the trail

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Americans wandered about in an unsystematic way for almost 50 years after coming to the trans-Mississippi country. This was the period of the fur trappers, the fabled mountain men who have such a gaudy reputation for pathfinding and trailblazing. It is true that the mountaineers did a lot of backcountry traveling and that the best of them could find their way from a beaver pond in Colorado to a Crow squaw in Montana. But any study of fatality records of the time also makes it clear that getting lost killed more trappers than rattlesnakes, Blackfeet and trade whiskey combined.

Even the mountain men who survived were not much help to the general citizenry. They tended to be jokey and illiterate, no more familiar with compasses than they were with harpsichords. By 1835 or so it was usually possible to find a crusty old character hanging about Independence, Mo., the staging area for would-be Western settlers, who for a shot of whiskey would tell you how to get to almost anyplace you wanted to go: Salt Lake, Old Faithful, the land of the Sasquatch. The difficulty was that you could go down the street to another bar and find an equally crusty character who would give you altogether different directions or advise that there was no such place. The situation illustrated a truth that is as old as civilization: you cannot have commerce, industry, agriculture, law, order, a nice vacation or even a proper country until you know where you are and have reasonably dependable maps available to all.

Mapless life in the Golden West came to general attention in the late 1840s, following the Mexican War. In this engagement Zachary Taylor, Winfield Scott, Ulysses Grant, Robert E. Lee, Stonewall Jackson and a lot of their friends beat on our southern neighbors in the name of Manifest Destiny until the Mexicans said, "O.K., Uncle. You win. What do you want?" "We would like a lot of your land," the Americans answered. "What parts and how much?" said the Mexicans.

The question was a stumper. The armies of the two nations had been slaughtering each other for two years to determine the ownership of certain parcels of real estate, the extent and precise locations of which were a mystery. The peace commissioners had no alternative but to rely on old Spanish maps, for the most part fanciful when drawn a century or so earlier and updated only with geographic gossip contributed by those mountain men. They were the kind of thing used today as place mats in economy motels, crude diagrams dressed up with random cartoons of folk dancers, harvest workers and leaping deer. Unimpressed, the commissioners called a halt to negotiations while an officer of the U.S. Topographic Corps, William Emory, went into the field to find out how the land lay between El Paso and San Diego. Emory proved a brilliant technician as well as a man of strong geopolitical opinions. Often at odds with the peace commissioners, generals and politicians, he not only mapped the country but played a considerable role in deciding who was going to own which portions of it.

There was such general relief at finding out at last where Tucson was and who held taxing rights to Tijuana that there followed an upsurge of interest in getting decent maps for the rest of the country. Yet not until another war had been fought did the period of the great surveys begin. By the late 1860s four ambitious reconnaissance parties were in the field. Army topographers, commanded by Lieut. George Wheeler, were in the Southwest among cacti and Apaches extending and consolidating Emory's work. John Wesley Powell, the one-armed Civil War veteran who would conquer the Grand Canyon, was sorting out the intricacies of the Colorado Plateau supported by private donations and small grants from government agencies. Clarence King, a well-connected Yale graduate, was surveying from California eastward along the 40th parallel under the auspices of the Army. Ferdinand Hayden, a physician turned free-lance explorer, had parlayed his gift for raising Congressional appropriations into a mapping expedition for Nebraska, the Dakotas and Wyoming.

The four survey chiefs were exceptionally competent. They not only drew their maps but brought along geologists, agronomists, biologists and anthropologists who contributed to the reports. These parties conducted the first systematic inventory of Western lands and resources, and in doing so made an immensely important contribution to future development and prosperity. However, each of the four surveyors thought very well of himself, and they quarreled incessantly, poached on each other's territories and duplicated much work. The competition became something of a public scandal, and was settled only by an act of Congress that knocked heads together and, in 1879, created the U.S. Geological Survey, a Department of the Interior agency that thereafter coordinated all mapping activities.

In its 95 years the Survey has picked up a variety of additional functions: research operations in geochemistry, geology, geophysics and hydrology: inventorying and conserving national water resources; the supervision of mining, gas and oil development on federal lands. But its first order of business obviously was to map the considerable tracts of the United States still uncharted in 1880 and to bring together existing maps and correlate them in a national cartographic matrix. Currently all of the United States, including Alaska and Hawaii, is covered by a series of 1:250,000-scale topographic quadrangle maps. Each is a one-degree-by-two-degree (latitude and longitude) rectangle encompassing between 4,500 and 8,500 square miles, depending upon its position relative to the equator. The one-inch-to-four-miles scale of the 250s, a recent series, makes them useful guides to comparatively large areas. (Common road maps generally have a one-inch-to-10-miles scale.) However, their scale is too small for precision topographic study. Therefore, work has been carried forth on two additional series of topos, which, combined, cover about 86% of the country. They are the 15s and the 7�s. Each 15 covers a 15-by-15-minute quad, or about one mile to one inch. The 7�s logically are 7�-by-7�-minute quadrangles. These exquisite maps portray between 50 and 70 square miles of land at a 1:24,000, or one-inch-to-2,000-foot scale. (Close to 60% of the United States has been reduced to 7� quads.)

Along with its basic topographic job, the Survey has branched off into special mapping projects, distributing maps concerned with earthquakes, geology, tides, soil composition, vegetation, sunshine, temperature, rainfall, mineral and energy resources, American history, population distribution, per capita income, time zones and administrative districts. These maps and many more are published in the National Atlas, one of the most useful (765 maps), heftiest (14 pounds) and least known (in part because it costs $100) of all federal reference volumes. The Survey is also into what might be called exotic mapping, involving itself, along with other agencies, in the mapping of Antarctica, the moon and Mars. (The aforementioned Hack, who first introduced me to topographic maps, is in fact Robert J. Hackman. Among other accomplishments he is the Survey scientist who led the team that compiled the first engineering geologic map of the moon.)

Fancy and exotic maps aside, the bread-and-butter product of the Survey is the 7�-minute series. These maps owe their preeminence to several factors, principally accuracy. According to standards adopted in 1941,90% of all points on a 7� quad must be placed within one-fiftieth of an inch accuracy tolerance. In terrain terms this means that wherever you are, you can expect to orient yourself on a map with no more than 40 feet of error. In fact, most Geological Survey maps published in the last 15 years are much more accurate than the 1941 standards require.

Perhaps the most impressive thing about the 7� is the wealth of detail they contain. By a combination of symbols and color codes such features as woodlands, orchards, pastures, swamps, sinks, glaciers, dunes, intermittent streams, rapids and springs are depicted. In rural, village, small-town and suburban areas, 'buildings down to individual dwellings and barns are indicated. In metropolitan areas where architectural features are so numerous and bulldozers so active, the structure references are less dependable. Roads from interstates down to old logging trails and footpaths appear, as do schools, churches, cemeteries, dams, footbridges, mine shafts, gravel pits, power and fence lines and federal, state, county, township, range and section boundaries.

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