I appreciate your suggestions. One thought that immedately occured to me when reading your post was to check out Charles Jennison and his cohorts. However, I have not been able to find any on-line version of the 1860 census for Linn County (Mound City is where I understand Jennison lived). Upon further thought, I think there will be some signfiicant limitations on getting insights into the economic aspects of jayhawking from the census data. The biggest era of jayhawking (in terms of taking wealth out of Missouri) occurred after the 1860 census, and by the time of the 1870 census, I suspect any economic impacts of jayhawking would be obscured by the upturn in the Kansas economy resulting from the war effort.