Tenure is a process in which teachers can become permanent teachers inside a school district after a certain amount of years of services.
This helps in protecting teachers who have given years of service to their specific school district. One protection is in order to be let go the district must have a hearing in front of the board. In order to be released from the job teachers must do something that is extreme to be let go.
Missouri does have a tenure where in five years you become a permanent teacher in that district.
Iowa does not have tenure instead has a provision called code 279 where the firing has to be shown a just cause. This means teachers can be let go by the acts of performance or high quality work. This can leave teachers vulnerable to school districts.
When it comes to myself picking a place of employment Iowa would not be high on the list. Seeing that a just cause can be a reason for removal is extremely difficult to feel protected. The teachers will be at the districts mercy when it comes to be fired. While if your in Missouri the process to relieve you from your position is extremely difficult to do. I would feel more likely to want to find a district and stay there to build your reputation and protection at the same time. Iowa seems to want to base everything on how the kids are doing which could be an easy scapegoat if someone in your building does not want you around.