Scott served Emerson in Missouri, a slave state.
Emerson transferred to Fort Armstrong, Illinois, a free state, with Dred Scott.
Emerson and Dred Scott moved to Fort Snelling, then part of Wisconsin, a free state.
The Scotts remained at Fort Snelling whilst Emerson transferred back to Fort Jesup, St Louis, Louisiana.
Dred Scott, the famous slave (public domain)