Mo. Rev. Stat. § 52.110

The collector shall keep his office at the county seat, except when meeting the taxpayers; provided, that in all counties in this state in which there is no bank located at the county seat and in which, according to law, two or more terms of the circuit court are held each year in some other town or city than the county seat and in which town or city are located one or more banks, the county collector may, at his option, keep his office in such town or city.