Extensive archive of approx. 200 documents, spanning 1840s-1940s (bulk 1840s-1870s), most  associated with prominent merchant and early Michigan settler Asa Kingsbury. Primarily includes business correspondence and documents addressed to the firm of Asa and Charles Kingsbury. Correspondence originates from businessmen throughout the Midwest including in Wisconsin, Michigan, Ohio, and Illinois, and from as far away as New York. Other merchants represented in the collection include Christian Henry Buhl (one-time Detroit mayor) of the firm Buhl & Ducharme in Detroit, Henry B. Baldwin of the firm H.P. Baldwin & Co. (one-time Governor of Michigan), and many others. A number of early southwest Michigan settlers are represented in the collection as well. 

Asa Kingsbury (1806-1883) was a Massachusetts native who followed business opportunities which ultimately landed him at Cassapolis, Michigan. Here he opened a successful dry goods business ca 1835 with his brother Charles Kingsbury joining him in the business in 1837. Asa Kingsbury's business dealings later extended into real estate through which he acquired large real estate holdings, and in 1855 he opened a private banking office.