September 13, 1841
President Tyler appointed James Duane Doty governor of the Territory in place of Dodge; another passage gives the appointment date as September 30, 1841.
Nation and worldGrade A · 1 independent source
The evidence
“The customary markets, Chicago and' Milwaukee, were both "a long way off," if dependence was to be placed only on the primitive ox or horse team, and the time consumed in travel added greatly to the cost of production, but not one farthing to the market price. The old problem was to be solved once more ; the producer and consumer were to be brought nearer together, in time if not in distance ; and the plain, rugged, common sense of. the prudent and thrifty class which had built up the prosperous settlements in ■ * Appointed Governor of the Territory by President Tyler September 13, 1841, and resigned his seat as delegate.”
1879-history-of-rock-county/10-rock-county-ch04-early-maps-courts-railroads.md, PDF p. 374 / book p. 378
Butterfield, C. W., et al. The History of Rock County, Wisconsin: its early settlement, growth, development, resources, etc. Chicago: Western Historical Company, 1879. Cornell University Library via the Internet Archive, archive.org/details/cu31924028871585.
Grade A: Found on a page of one of our sources