The Central Bureau of the Map of the World was created in 1913 to act as a liaison agency for the countries interested in the publication of maps on the scale of one to one million, or approximately 16 miles to the inch.
European countries and the United States have been engaged for some years in making surveys and publishing topographic maps, but different scales have been used in the same country, or in the several countries, and the maps have not been easily comparable. In the early years of map-making by the United States government many maps were published on the scale of 1 to 250,000, or four miles to the inch; later the scale was increased to 1 to 125,000, or two miles to the inch, but during recent years the standard scale has been 1 to 62,500, or one mile to the inch, except for maps designed for special uses where other scales have been deemed desirable.
The publication of the map of the world on the scale of one to one million is not a co-operative undertaking for the production of a single map, but embodies the issuance of a series of maps of a uniform scale and size. Each country publishes the maps showing its territory, except that if a standard map shows an area in two or more countries, the determination regarding the publishing country is a matter of mutual agreement.
Each map represents an area embracing four degrees of latitude and six degrees of longitude, except that north or south of 60° latitude the width of the map may be any multiple of six degrees of longitude, as the degrees of longitude become progressively narrower as the poles are approached.