Nicollet encountered financial and professional difficulties resulting from political turbulence in France following the July Revolution (1830) and the rising dominance of physics as a laboratory science. Penniless, he emigrated to the United States in 1832, sailing from the port of Brest. Nicollet hoped to boost his reputation among European academics through his work in the US. He intended to make a "scientific tour" of the country and had a goal of using his expertise to accurately map the Mississippi River Valley. He arrived in Washington, D.C., where he met with scientists and government officials, discussing scientific surveys of the country. He traveled to New Orleans, from where he intended to proceed to St. Louis, Missouri, but due to a cholera outbreak, travel by steamboat was practically halted. Instead he spent the next three years traveling throughout the south, primarily between New Orleans and Baltimore. Nicollet finally arrived in St. Louis in 1835.