English: Maclure's 1817 Geological Map of the United States, which accompanied the article 'Observations on the Geology of the United States of North America; With Remarks on the Probable Effects That May Be Produced by the Decomposition of the Different Classes ofRocks on the Nature and Fertility of Soils: Applied to the Different States of the Union,Agreeably to the Accompanying Geological Map' published in Transactions of the American Philosophical Society, New Series, Vol. 1 (1818), pp. 1-91. This is the most common version, which also appeared in a privately published edition of the article, in 1817 and in subsequent reprints of 1822 onwards which have a different base map.