History of Maps
The oldest surviving maps are maps from Mesopotamia made on clay tablets and maps from ancient Mediterranean cultures made on mosaic tile. The writings of ancient Greece and Rome refer to other maps, but these were drawn on perishable parchment or paper, and the originals have disappeared. Some early maps have survived, however, by being copied and recopied. Still extant are medieval copies of an ancient geography text attributed to Ptolemy of Alexandria, who lived in the 2nd century AD. Ptolemy's text contains maps drawn on a type of conic projection and information on locations and the effects of latitude.
Medieval European cartography was less advanced than that of ancient times. Many maps made in the Middle Ages were of the "T in O" variety. Maps of this type were bordered by a circle of ocean, and had a "T"-shaped body of water in the center that separated Asia from Europe and Africa. Asia was above the "T"; Europe, to its left; Africa, to its right. East was at the top, with Jerusalem and the Holy Land as seen from Europe the obvious center of interest.
The development of trade during the Renaissance was accompanied by the appearance of the practical sailing charts known as portolanos. These were first used in southern Europe during the 13th century. They showed coastlines fairly accurately and were covered with lines and compass roses giving the main directions. Improvements in practical astronomy and the development of trigonometry brought better surveying methods and the mathematical tools for creating new map projections. Printing and engraving, which also originated during the Renaissance, made maps cheaper and more abundant.
Although far superior to earlier maps, the maps of the Renaissance left much to be desired. Imaginary continents and islands were drawn to fill in extensive blank areas. The unexplored interiors of known land areas were covered with fanciful detail. Borders were decorated with pretentious artwork. The latitudes of Renaissance maps were generally accurate, but the distorted shapes of some coastlines show that longitudes were not.
In the late 17th century, when newly developed astronomical techniques were used to ascertain longitude, the relative locations of many places were accurately determined for the first time. This, combined with continued exploration of the seas, made possible the more accurate coastlines of 18th-century maps. The unknown continental interiors were largely filled in as a result of 19th-century land explorations. Scientific atlases with thematic maps now appeared. These were a great stimulus to the scholarly study of the Earth. More recently, the use of power-driven presses, lithography, and photoengraving in the printing of maps has made them cheaper, more colorful, and more detailed than ever.
Many improvements in mapping coverage during the 20th century have been made through international cooperation. The pre-World War II International Map of the World (IMW) project is a prime example. Many IMW sheets, using a scale of 1:1,000,000 and a standard projection and set of symbols, were completed either by governmental or private agencies. The Inter-American Geodetic Survey, a joint venture between the United States and various Latin American governments, also had produced accurate maps of various areas in the Western Hemisphere by the late 1960s. Nevertheless, not all of the world has been mapped at a large scale, and even small-scale coverage on widely used maps, particularly those of the underdeveloped countries, is often not accurate.
Many nations and some of the states of the United States have published atlases of high-quality thematic maps. For example, the National Atlas of the United States, published in 1970, contains many excellent physical, historical, and socioeconomic maps.