I have quite a few SMITHs marrying into my lines in and around Grant County. Let me know if you recognize anyone below - and I'll try to give you an idea of where they all ended up.
James ROGERS married Elizabeth SMITH (sister of George SMITH). They had 4 children that I know about, and were buried in Parker, Turner County, South Dakota.
Jennie ROGERS married Lafayette SMITH (b. 05 Jul 1859, d. 15 Nov 1914). They had 5 children that I know about, and were buried in Mount Vernon, Davison County, South Dakota.
Emma ROGERS married George SMITH (brother of Elizabeth SMITH). They had 1 child that I know about, and were buried in Emmetsburg, Palo Alto County, California.
James, Jennie, and Emma are all siblings with roots in Grant County.
I don't know if this helps you at all, but shows a little bit of migration with the correct surname.