Missouri Revised Statutes Title IX. Suffrage and Elections § 115.133. Qualifications of voters

1. Except as provided in subsection 2 of this section, any citizen of the United States who is a resident of the State of Missouri and seventeen years and six months of age or older shall be entitled to register and to vote in any election which is held on or after his eighteenth birthday.

2. No person who is adjudged incapacitated shall be entitled to register or vote. No person shall be entitled to vote:

3. Except as provided in federal law or federal elections and in section 115.277, no person shall be entitled to vote if the person has not registered to vote in the jurisdiction of his or her residence prior to the deadline to register to vote.