The Missouri Secretary of State website has links to state-wide petitions and initiatives; however, since ballots questions and candidates vary by county and district, a voter must go through the local county elections office to find sample ballots, as of 2015.
The Missouri Secretary of State website has links to the election clerk websites for each county. Some counties, such as Greene County and Boone County, have links to the ballot initiatives and candidates for each district. The state website also has a voter registration link so a person can find out if she is registered to vote and, if so, which district within her county she would vote in.
Sample ballots are also available at the local election clerk's office and at the polling place on election day. According to the Secretary of State election Frequently Asked Questions page, newspapers in general circulation must print sample ballots twice before each election.