In theory, 'secret ballots' (formally known as Australian ballots where they were first used in late 1880s/early 1890s) make for 'free elections' because they reduce/eliminate pressure exerted upon voters casting public vote. Proponents cited threats of retaliation coercing voters into choosing against their choice of candidates.
Prior to adoption, parties prepared different colored tickets (hence, term 'straight ticket' voting) and passed them out to voters at polls. Effect of Australian ballot - in concert with turn-of-20th century 'reforms' such as voter registration, nonpartisan elections, at-large election, 'reforms' - was reduced immigrant, working class, less- formally educated voter turnout.
Under changed electoral system, first-generation non-English speaking immigrants (who comprised 2/3rds of US industrial proletariat in early 20th century) had to register to vote in writing, usually months prior to election, and were confronted at polls with printed ballot they might not be able to read.
In South, racist motive existed for adopting 'secret ballot' as popular Democratic Party campaign song of time indicates: The Australian ballot works like a charm It makes them think and scratch And when a Negro gets a ballot He has certainly met his match
Adoption of 'secret ballot' placed ballot preparation in hands of government. Ballot format is significant matter (or should be). *Office-block* (Massachusetts) ballot groups candidates together under offices they seek. *Party-column* (Indiana) ballot arranges candidates names in one column based on party affiliation. Former, used in about half of US states, deemphasizes party affiliation, discourages 'straight ticket' voting, and is associated with lower voter (smaller working class) turnout. Michael Hoover