Upper Peninsula of Michigan was granted to Michigan. The U.S. Congress created the Wisconsin Territory in 1836 and appropriated funds to conduct a survey to determine the boundary between Wisconsin and Michigan. In 1840, Cram and Douglass Houghton led the boundary survey team up the Menominee River to its source at Brule Lake. A previous map incorrectly listed Lac Vieux Desert as the headwater of the Menominee River and the Montreal River. He negotiated a treaty with the Ojibwa Chief Ca-sha-o-sha which allowed the survey to continue. The survey could not be completed in 1840 due to errors in the map used by Congress to determine the boundary. Cram returned to the Upper Peninsula in 1841 to continue the survey. He identified Lac Vieux Desert as the source of the Wisconsin River and recommended a different boundary between Wisconsin and Michigan. Congress used the border recommended by Cram when they passed the Wisconsin Enabling Act of 1846 prior to Wisconsin becoming a state in 1848. Michigan refuted the results of the survey and claimed that Cram's interpretation of the boundary cheated Michigan out of 800 square miles of land. The case reached the U.S. Supreme Court in 1926 and was decided in favor of Wisconsin. In 1841, Cram participated in the United States Lake Survey. His portion of the survey began at Green Bay and moved south toward Chicago while William G. Williams began his portion at Green Bay and moved north toward Mackinac Island. In 1843, Cram conducted work in Louisville, Kentucky to improve navigation of the falls on the Ohio River. Cram recommended the expansion of the canal and construction of a second canal to provide two way river traffic, however the recommendations were not approved by Congress and were not implemented. In 1844, Cram was assigned to improve the harbor works at St. Louis, Missouri. The harbor required improvements since the flow of the Mississippi River had formed sandbars that trapped ships or required long diversions to avoid them. He proposed several works to remedy the situation but they were deemed too experimental and expensive. The construction of a dam was selected and work began on it until the outbreak of the Mexican American War. In 1845, Cram served as chief topographical engineer in the Army of Occupation under General Zachary Taylor during the Mexican American War. He conducted systematic topographic surveys of the Nueces River, the