The duration of a divorce in Missouri varies from case to case. Factors that determine length include how contested the case is, the cooperation of the parties, whether or not there are two attorneys involved, the complexity of the issues, whether or not there are issues of abuse or neglect of children and the appointment of a guardian ad litem, whether or not the case goes to trial, the county where the case is filed, involvement of experts, and other case specific factors.
On the short end, a Missouri divorce case that is completely uncontested, where only one party is represented by counsel, and the parties have signed written agreements for parenting matters (parenting plan), child support, property and debt division, and maintenance, can be completed in most cases in about 45-60 days from the date of filing, depending on the county. Note however that the length of time that is spent negotiating, drafting, and reviewing the agreements may add some time to this.
For a contested Missouri divorce case, where the parties are not in agreement at the beginning, but eventually come to an agreement resolving all of the issues without trial, the time frame usually runs in the range of 6 months, but again is county and case specific.
For a contested Missouri divorce case that goes all the way to trial, not counting post trial motions, appeals, or further proceedings, will often take between 6 months and 1 year, but could easily exceed that time frame depending on the county and the complexity of the case. In the event of appeal of a tried divorce case, the time frame will almost always exceed 1 year.
Note that there is a statutory 30 day waiting period for all Missouri divorce cases which starts on the day of filing, but it is rarely that even an uncontested case is completed this quickly, as the dockets of most courts will exceed the minimum waiting period.