Contemporary natural historical depictions of North America are rare from the middle of the 18th century or earlier. One of the few authors who made first-hand observations was the Finnish-born Professor of Economics Pehr Kalm. He explored the eastern parts of North America, especially in 1748 and 1749 and early 1750. Travelogues and diaries written by him were published in Swedish. Further, Kalm wrote several important articles about his observations in Swedish. He also supervised dissertations presenting the economic benefit colonies in North America could provide. The writings have been discussed in various contexts and some have been translated into English. But no summary has been compiled of the natural history findings made by him.

Kalm’s expedition was financed by the Royal Swedish Academy of Sciences. The instructions included not only writing down all natural history details, but also social and everyday life issues. The task was also to collect zoological and especially botanical specimens as well as seeds of economically useful plants to be tested in Sweden. The Academy’s guidelines were part of the Swedish government’s economic policy, the goal of which was to increase domestic production. Here, the Academy relied on the assessment of its founding member, Carl Linnaeus, of the benefits of the expedition. He had a strong additional motive to acquire new species for science.

In this article, we bring together botanical (including most economic botany), zoological, ecological and other natural historic observations made by Kalm and examples of how this unique amount of information has been used. The summary is based on Kalm’s travelogues, diaries, articles, supervised dissertations and herbarium specimens collected by Kalm maintained at the Uppsala Museum of Evolution. The diaries have not been translated into other languages. They have much more information compared to the travelogues. In addition to this, we bring up a few additional topics, such as Kalm’s observations on climate change, fossils, geology, northern lights, weather and phenological observations. Useful plants and alien species are written about in separate articles.