Rubuta ci gaba ga wannan sakin layi - Nicollet ya fuskanci matsalolin kudi da na sana'a sakamakon rikice-rikicen siyasa a Faransa bayan juyin juya halin Yuli (1830)
da kuma karuwar rinjaye na kimiyyar lissafi a matsayin kimiyya na dakin gwaje-gwaje. Ba tare da kuɗi ba, ya yi hijira zuwa Amurka a 1832, ya tashi daga tashar jiragen ruwa na Brest. Nicollet ya yi fatan haɓaka martabarsa a tsakanin masana kimiyya na Turai ta hanyar aikinsa a Amurka. Ya yi niyyar yin "tafiya ta kimiyya" ta ƙasar kuma yana da burin yin amfani da ƙwarewarsa don zana taswirar kwarin Kogin Mississippi daidai. Ya isa Washington, DC, inda ya sadu da masana kimiyya da jami'an gwamnati, suna tattauna binciken kimiyya na kasar. Ya yi tafiya zuwa New Orleans, daga inda ya yi niyyar ci gaba zuwa St. Louis, Missouri, amma saboda barkewar cutar kwalara, tafiya ta jirgin ruwa ya tsaya. Maimakon haka ya shafe shekaru uku masu zuwa yana tafiya a duk kudancin, musamman tsakanin New Orleans da Baltimore. Nicollet ya isa St. Louis a ƙarshe a 1835.