File:A Section of the Map of the Map of North America (Aaron Arrowsmith 1814).jpg

From 1791 to 1857 the Arrowsmiths published at least 15 editions or revisions of their maps of North America and British North America. The changes from one edition to another normally did not require redrawing the master map, although this was done as required. The maps generally were kept updated simply by inserting into the existing map new information supplied by Hudson’s Bay Company traders and surveyors, and other explorers. By studying the various Arrowsmith maps in their proper succession one can learn something of how the geographical knowledge of the interior of North America grew. The occasional jumps in knowledge are perhaps best illustrated by the 1802 and 1814 maps. In 1802 very little exact data of present day Manitoba was available in London: Lakes Winnipegosis, Manitoba, and Winnipeg are very distorted 1802 map. But by 1814 Lake Winnipeg is more accurately drawn, and so is Lake Winnipegosis, though Lake Manitoba is still misshapen. There are few differences between the two maps along the Hayes river, but more information has become available on the Nelson and Churchill rivers. It is especially noteworthy that the Lewis and Clarke expedition of 1804-1806 contributed a great deal of information on the Missouri river area. The heights of land are often prominently depicted on maps of this period, as they are on these. Unfortunately, they are frequently so exaggerated that they look like ranges of hills. (Warkentin and Ruggles. Historical Atlas of Manitoba. map 54, p. 140)

A map exhibiting all the new discoveries in the interior parts of North America / inscribed by permission to the honorable governor and company of the adventurers of England trading into Hudsons Bay, in testimony of their liberal communications to their most obedient and very humble servant A. Arrowsmith, hydrographer to H.R.H. the Prince of Wales, January 1st 1795 ; Puke, sc. Additions to 1814. Drawn by Aaron Arrowsmith, No. 24 Rathbone Place. Coloured. Puke, sc. Image Source: Library of Congress American Memory Project